Sunrise & Sunset Calculator

What this tool computes

Give it a place — a town name, or a latitude, longitude pair typed straight in — and a calendar date, and it works out the key moments of the Sun's day at that place: civil dawn, sunrise, solar noon, sunset, the start of the evening golden hour, civil dusk, and the total length of daylight. Every value recomputes the instant you change the coordinate, the date or the time zone, so you can scrub through a year and watch the days stretch and shrink.

Typing a town instead of a coordinate

The Town or city box is a shortcut into the same latitude, longitude field beside it, not a second calculator. Pick a suggestion and it writes that place's coordinates into the coordinate box, and every readout on this page recomputes exactly as if you had typed the numbers yourself. It searches 171,041 places from GeoNames — every populated place of 1,000 people or more. The 29,919 with 18,000+ people load on your first keystroke; the other 141,122 live in 18 alphabetical slices that are fetched only when that main list cannot answer what you typed, so Roskilde costs one download and Skagen (about 7,000 people) costs one more of roughly 100–130 KB compressed. A small-town pick also sets the Time zone picker to that town's own zone — Skagen gives Europe/Copenhagen — and so does a city pick. Accents are optional, so malmo finds Malmö and tromso finds Tromsø, and a country or a US state code breaks a tie on a common name: Roskilde Denmark, Roskilde, Denmark and Springfield MA all resolve. Every suggestion is labelled with its country, so two San Franciscos never look identical.

Three limits are worth knowing before you trust it. Matching is exact, not fuzzy — every word you type has to appear in the name — so a misspelling finds nothing rather than confidently finding somewhere else. That is the deliberate trade: a sunrise time for the wrong town looks exactly as plausible as one for the right town, and there is no way for you to tell from the readout. Names in non-Latin scripts are searchable only in their own script; there is no transliteration table, so Cyrillic, Greek, Arabic and CJK names need their own characters. And the coordinates sit on a 0.01-degree grid, about 1.1 km — a town centre, not a street address. That grid costs 2.4 seconds of clock time per 0.01° of longitude, because the Sun's hour angle moves 15° an hour, plus a latitude term that is largest at the solstices: 0.01° of latitude moves midsummer sunrise by 3.4 seconds at London and 4.5 seconds at Roskilde, and by about a tenth of a second at either place near the equinox. All of that is far inside the roughly one minute this page claims against an almanac — but if you need a specific address rather than a town, type its coordinates.

The town list is a 715 KB file and it is fetched on your first keystroke in that box, never when the page loads, so the first screen costs nothing extra and a visitor who only ever types coordinates never downloads it. If it will not load — you are offline, or the request is blocked — the box disables itself and says so in one line, and the coordinate field, Use my location and the five city buttons carry on working exactly as they did before it existed.

The astronomy behind it

The calculator uses the solar-position algorithm published by NOAA's Global Monitoring Laboratory, itself a streamlined version of the equations in Jean Meeus' Astronomical Algorithms. Two quantities do most of the work. The first is the Sun's declination — how far north or south of the celestial equator it sits on a given date, swinging between +23.4° at the June solstice and −23.4° in December because Earth's spin axis is tilted about 23.4° to its orbit. The second is the equation of time, a correction of up to about ±16 minutes that captures how Earth's elliptical orbit and axial tilt make the real Sun run ahead of or behind an even-ticking clock. From those two figures, plus your latitude and longitude, the tool solves for the hour angle at which the Sun's centre sits 90.833° from straight overhead — that extra 0.833° is the standard allowance for atmospheric refraction lifting the Sun's image near the horizon (about 34 arc-minutes) plus the Sun's own apparent radius (about 16 arc-minutes).

Why times shift with latitude and season

Sunrise and sunset are not fixed because the Sun's daily arc across the sky changes shape through the year. When the Sun's declination is high in June, the Northern Hemisphere tips toward it: the Sun climbs higher at noon and traces a longer path above the horizon, so it rises early and sets late. In December the geometry reverses and days are short. Latitude sets how dramatic this is. Near the equator the Sun rises and sets at a steep angle and day length barely moves across the year — always close to 12 hours. Move toward the poles and the swing grows, until above the Arctic and Antarctic circles (about 66.5°) the Sun can fail to set at all around midsummer (the midnight sun) or fail to rise around midwinter (polar night). Run the same date, 21 June, through this tool and the pattern is stark: Quito on the equator gets about 12 h 07 min of daylight, London (51.5°N) about 16 h 38 min, and Tromsø in northern Norway (69.6°N) reports the midnight sun — the Sun simply never sets. This tool reports those two cases explicitly instead of inventing a time that does not exist.

Worked example: London on the June solstice

Enter London at 51.5074, -0.1278, the date 21 June, and set the offset to UTC+01:00 (British Summer Time). The tool returns roughly:

Two things are worth noticing. Solar noon lands at 13:02, not 12:00 — one hour of that is the BST offset, and the rest is longitude and the equation of time. And the day is over 16½ hours long: at London's latitude the midsummer Sun sits high and its arc is broad. Run the same location on 21 December and daylight collapses to under 8 hours — the same place, the same maths, an eight-hour swing driven entirely by the axial tilt.

Solar noon, twilight and the golden hour

Solar noon is the true middle of the day — the Sun at its highest, due south from the Northern Hemisphere. It is the anchor the algorithm builds everything else around: sunrise and sunset are symmetric about it, each offset by the same hour angle. Civil twilight brackets the usable low-light periods: civil dawn is when the Sun's centre first climbs to within 6° below the horizon in the morning, and civil dusk is when it drops back past that line in the evening — the window when there is enough scattered light to move around outdoors without lamps. The golden hour is the softer, warmer stretch when the Sun is low but still up; this tool flags the evening golden hour as the moment the Sun descends to 6° of elevation on its way down, which photographers use as the cue that the flattering light has begun.

Golden hour, blue hour and solar noon — the photographer's readouts

The Photography light windows block turns the same solar geometry into the three moments photographers actually plan around. The golden hour is defined here the standard way: the span while the Sun's centre sits between 4° below and 6° above the horizon. Sunlight then travels through so much atmosphere that the blue wavelengths scatter away, leaving warm, low-angle light with long soft shadows — it happens twice, climbing through that band after dawn and descending through it before dusk. The blue hour is the adjacent twilight band, Sun 6° to 4° below the horizon: no direct sun at all, but the upper atmosphere still glows an even deep blue that suits cityscapes and long exposures. Despite the names, neither lasts an hour by right: at London on the June solstice the evening golden hour runs about 83 minutes (20:27–21:50 BST) and the blue hour under 20, while near the equator — where the Sun crosses the bands at the steepest angle possible — the golden window bottoms out at about 40 minutes, the geometric floor set by the fact that the Sun's altitude never changes faster than 15° per hour. Solar noon is repeated in this block as the opposite cue — the Sun at its highest, shadows at their shortest and hardest, generally the least flattering outdoor light of the day.

Two honesty notes. First, the windows are geometric: real refraction near the horizon varies with air temperature and pressure, so treat the edges as good to about ±1–2 minutes — the light itself fades in and out gradually anyway. Second, at high latitudes these bands are not guaranteed to occur. Around Svalbard's midsummer the Sun never sinks to +6°, so there is no golden hour at all; in its midwinter the Sun never climbs to −6°, so there is not even a blue hour; and in the shoulder seasons the Sun can peak inside the golden band, making the entire short day golden light. The tool detects each of these cases and says so in plain words — a window that does not exist is reported as such, never as a fabricated time.

The three twilight bands, and when they do not happen

Below sunset the sky does not simply switch off, so astronomers split the fade into three bands by how far the Sun's centre has sunk below the horizon. Civil twilight runs to −6° — the point where you can no longer comfortably read a newspaper outdoors, and roughly when street lighting and car headlights become useful. Nautical twilight runs to −12°, and the name is literal: down to that depth the sea horizon is still a discernible line against the afterglow, so a navigator can hold a sextant on a star and measure its altitude against it. Astronomical twilight ends at −18°, the depth below which sunlight no longer measurably brightens the sky — the moment the faintest galaxies and the Milky Way's dust lanes come out, and the practical start of a deep-sky imaging session. The Twilight table above prints both the dawn and the dusk crossing of all three, on the clock you selected.

Two things are worth knowing before you plan around them. First, the darker the band, the longer it takes to cross: at London on the March equinox civil dawn is 05:29 UTC, nautical dawn 04:50 and astronomical dawn 04:09 — about 40 minutes apart each step, and the evening mirrors it. Second, these bands are not guaranteed to occur. London gets no astronomical twilight at all on 60 nights of 2026, from 23 May to 20 July: on the June solstice the Sun bottoms out near 15° below the horizon at solar midnight, so it never reaches −18° and the sky never becomes truly dark. Push further north and the effect swallows the other bands too — at Tromsø (69.65°N) on 21 June the Sun stays above −6°, so not even civil twilight ends. The table says so in plain words rather than printing a dash. The reverse case is just as instructive: Tromsø's polar night is not 24 hours of blackness. On 21 December the Sun never rises there, yet civil twilight still runs 09:31–13:53 local time — several hours of usable blue-grey daylight — with nautical twilight from 07:47 and astronomical from 06:28. One caveat if you are planning around the −18° band specifically: darkness is only half of what a stargazer needs, and the stargazing night planner supplies the other half by subtracting the minutes the Moon is above the horizon from that same window — at Roskilde on 20 September 2026 it turns 7 h 23 m of astronomical night into 4 h 54 m that are genuinely moonless.

The whole year: daylight chart and printable table

Under the day’s result, The whole year runs the same calculation for every day of the year — 365 rows, or 366 in a leap year — for the place and horizon you entered. The chart reads like a sky diary: each thin column is one day, local clock time runs from midnight at the top to midnight at the bottom, and the bands are night, astronomical, nautical and civil twilight and daylight, darkest to lightest. The orange lines are sunrise and sunset. Point at or tap the chart, or focus it and use the arrow keys, to read any single day; the table underneath prints sunrise, sunset and day length for all twelve months, marks today, and fits on two A4 or Letter pages from the Print table button. Copy table puts the year on the clipboard as tab-separated text that pastes straight into a spreadsheet; the CSV adds solar noon, civil dawn and dusk and the UTC offset for every date.

Pick a time zone and every date is read on the offset that zone is on at local noon that day, so summer time shows up as two visible steps. Copenhagen in 2027 is the worked example: sunrise is 05:54 on Saturday 27 March and 06:51 on Sunday 28 March, because the clocks went forward overnight, and the reverse hour comes back on 31 October. The same year gives Copenhagen its longest day on 21 June (17 h 32 min) and its shortest on 22 December (7 h 01 min) — yet the earliest sunrise is 18 June and the latest sunset 24 June, the earliest sunset 15 December and the latest sunrise 29 December, the equation-of-time offset that the FAQ below explains. If you set the offset by hand instead, the page keeps that one offset all year and says so above the chart: a fixed offset cannot know when your summer time starts.

Far north the chart shows what a table of times cannot. Tromsø (69.65° N) gets 48 days of polar night in 2027 — 1 to 14 January and 28 November to 31 December — and 69 days of midnight sun from 18 May to 25 July; those stretches are labelled on the chart and the table says polar night or midnight sun rather than inventing a time. Polar night is not drawn black: a band of civil twilight still crosses noon, because the Sun is only a few degrees below the horizon. The first and last midnight-sun days can differ by a day or two from other almanacs, since the Sun only grazes the horizon at midnight on those dates and the standard refraction allowance decides which side of it the day falls. Downloads are an SVG for documents, a 2400×1440 PNG for sharing, and the CSV — all generated in your browser from numbers already on the page, nothing uploaded. A link copied with Copy shareable link carries the place, the time zone and the year you chose.

Why the days stretch fastest around the equinox

The Day length readout shows today's daylight and, next to it, the signed change against yesterday. That number is far from constant. The Sun's declination traces a sine wave through the year, and a sine wave changes fastest as it crosses zero — at the equinoxes the declination shifts about 0.4° per day, while at the solstices it is momentarily stationary. That is why the solstice feels like a fortnight of identical days and the equinox weeks feel like the light is visibly returning. Latitude then multiplies the effect. Running London (51.51°N) through 2026 day by day, the fastest gain is about 3 min 59 s of daylight, around 18 March; on the June solstice the same city gains about 2 seconds, and in the days just after it starts losing a handful. At the equator the readout stays near zero all year — day length there never strays more than a few minutes from 12 hours. Inside the Arctic Circle the curve breaks entirely: once you are in midnight sun or polar night the daily length is pinned at 24 h or 0 h, so the change reads unchanged from yesterday until the Sun starts crossing the horizon again.

Standing higher: the horizon dip correction

Sea level is a special case, not the general one. Climb h metres above it and the horizon stops being at eye level: it drops below you by an angle called the dip, because your line of sight to it is tangent to a curved Earth. The Sun clears a dipped horizon before it clears a sea-level one, and it sets after. Fill in the optional Your elevation field and the tool applies exactly that: the sunrise/sunset threshold moves from the standard −0.833° to −0.833° minus the dip, and each time is labelled with how many minutes the height bought you.

The geometry is a single right triangle. You, the centre of the Earth and the point where your sight line grazes the surface make a right angle at that tangent point, with hypotenuse R + h and adjacent side R — so dip = arccos(R / (R + h)). One refinement keeps it honest: the same dense near-surface air that earns the 0.833° refraction allowance also bends your own horizontal sight line downward, pushing the visible horizon further off and making the real dip smaller than the vacuum value. The standard fix is an effective radius R/(1 − k) with k ≈ 0.17, which reproduces the dip table printed in every nautical almanac — 1.76 arcminutes per square root of a metre. In round numbers: 10 m gives 0.09°, 100 m gives 0.29°, 1,000 m gives 0.92°, 2,500 m gives 1.46°, and the summit of Everest at 8,849 m gives 2.75° — with the horizon then 369 km away.

How much clock time a given dip is worth depends on how steeply the Sun crosses the horizon, so latitude and season matter as much as height. Run these five yourself:

Ben Nevis is the instructive row. It is barely a third of Fuji's height and its dip is little more than half as large, yet its midsummer sunrise moves further — because at 57°N in June the Sun rises at a shallow, slanting angle and takes far longer to climb that last degree, while near the equator it comes up almost vertically and crosses any dip in minutes. That also means the correction is not a fixed number for a place: Denver gains about 7 minutes in January and a little over 7 in June, but a Scottish summit swings from a few minutes in winter to twelve in June. And because sunrise moves earlier and sunset the same amount later, the day length readout gains roughly twice the single-event shift — 24 minutes of extra daylight on Ben Nevis at midsummer.

What your horizon does not change, and why the rest of the page stays put: solar noon is a meridian transit, fixed by your longitude and the equation of time — the Sun is in the same place at the same instant whether you are on the beach, on the summit above it or in the shadow of a tower block, so neither the dip nor a skyline angle is applied there. Nor is either applied to the −6°/−12°/−18° twilight bands or the −4°…+6° golden and blue hours: those are defined as angles of the Sun measured from the astronomical horizontal, not as sightings of the visible horizon, and nothing on the ground moves the Sun. A ridge does of course keep you in its shadow — but that is a fact about your spot, not the definition of civil twilight, and inventing a shift in those rows would be a lie the numbers cannot support. So every readout below Sunrise, Sunset and Daylight is byte-for-byte identical at every horizon setting, by design and by test.

The bigger correction: the skyline you actually have

Height is the small term. What is in the way is the large one. Denver’s 1,609 m of altitude buys about 7 minutes of extra morning; five degrees of ridge to the east costs about 35 minutes at London’s latitude on the equinox — five times as much, from an obstruction you could walk to. That is why this page now has two more optional fields: Sunrise-side skyline ° and Sunset-side skyline °, the angular height above level of whatever blocks the view in each direction. They are separate because horizons rarely are symmetric: a valley floor can have a wall to the east and open water to the west.

The solver treats your skyline as the horizon. Sunrise is the instant the Sun’s upper limb appears over it, so with the skyline at a degrees the Sun’s centre has to reach

The refraction term is the part a naive “just add the ridge angle” version gets wrong. Refraction is 34′ only for a ray grazing the horizon and falls away fast: about 9.7′ at 5° and 5.3′ at 10°. The page uses Bennett’s formula for it, normalised so that a skyline of exactly 0° reproduces the flat-horizon −0.833° threshold to the digit — type 0 and nothing changes, which is the point.

What a given angle costs depends on how steeply the Sun climbs, so latitude and season matter as much as the angle itself. Every figure below is this page’s own output:

Quito is the floor: on the equator the Sun rises almost vertically, so it climbs through a 10° obstruction in 42 minutes. Reykjavík in midsummer is the other extreme — the Sun crawls up at a shallow slant and the same 10° hides it for over two and a half hours. At high latitude in winter an angle can block the Sun entirely; if that happens the tool says “Never clears your skyline” rather than mislabelling it polar night, because a flat horizon there would still have given you a sunrise.

How to estimate your angle — and what this cannot do

The tool cannot know your angle; there is no terrain database in a page that fetches nothing. You supply it, and one line of trigonometry is enough: the angle is arctan(height above you ÷ horizontal distance), both read off a topographic map or any mapping app that shows elevations. A ridge whose top is 400 m higher than where you stand and 2 km away is arctan(400/2000) = 11°; a 30 m office block 60 m down the street is arctan(30/60) = 27°. A phone clinometer app gives the same number directly if you can see the skyline. Precision is not the issue — near the horizon each extra degree is worth roughly 7 minutes at London’s latitude, so a degree of error is a few minutes, not an hour.

The honest limits, stated plainly because they are real. This is one angle per direction, not a skyline profile: a jagged ridge, a notch, a gap between two towers or a tree line that thins out will all let first light through earlier than a single number predicts. The rising azimuth also moves through the year — at London the June sunrise bears about 50° and the December one about 130°, an 80° swing along the skyline — so the ridge the December Sun comes over may not be the one you measured in June; for careful work, measure the angle along the azimuth you care about, on the date you care about. And the correction applies to direct sunlight on your spot: an eastern wall delays the moment the Sun touches you, but the sky above you brightens on the normal schedule, which is exactly why solar noon and the twilight bands below do not move. Leave both fields blank and every number on this page is what it always was.

Honest limits

This is a clear-sky geometric model, and it is honest about what that excludes. It assumes the standard 0.833° of horizon refraction, so genuinely unusual air temperature or barometric pressure can move the real sunrise by a minute or more. It models your height above sea level (the horizon dip) and the terrain in front of you: give it the angular height of your sunrise-side and sunset-side skyline and the crossing is solved against that instead of against a flat horizon. What it still cannot do is know that angle for you — there is no terrain database in a page that fetches nothing — and what you give it is a single angle per direction, not a profile of your skyline, so a jagged ridge, a notch or a gap between buildings will let first light through earlier than one number predicts, and an angle measured in June may not be the part of the ridge the December Sun clears. Blank fields mean a clean unobstructed horizon, which is the assumption every generic sunrise table makes silently. It ships no time-zone data of its own, and it no longer makes you guess one either: the optional zone picker reads your browser's copy of the IANA database through Intl, works out the offset for the date you entered, prints it beside the zone's abbreviation and leaves it editable — so the summer-time hour is handled, but only as well as that browser's copy handles it, and for a date years out that copy is projecting today's rules forward. For the overwhelming majority of places and dates the results land within about a minute of an official almanac, which is plenty for planning a shoot, a hike, a garden or a prayer time — but for surveying-grade precision, or for the exact instant behind a real skyline, consult a dedicated ephemeris. And near the poles, on any date the Sun never crosses the horizon, the tool tells you it is polar night or midnight sun rather than printing a sunrise that does not happen.

Pair it with the rest of the sky

Sunset is the start of the observing night. Once the Sun is down and civil twilight has ended, the Moon Phase Calculator shows how much moonlight will compete with the stars — a bright full moon near the horizon can wash out all but the brightest — and the free star map generator plots the constellations and planets on view from your latitude at any moment. Use this page for when it gets dark, and those two for what you will see once it does.

Frequently asked questions

How does this calculator work out sunrise and sunset?

It uses the solar-position algorithm published by NOAA's Global Monitoring Laboratory, a simplified form of Jean Meeus' Astronomical Algorithms. From the date it computes the Sun's declination and the equation of time, then solves for the moment the Sun's centre reaches 90.833° from the zenith — 90° plus 0.833° for the standard allowance of atmospheric refraction and the Sun's apparent radius at the horizon. If you supply an elevation, the horizon dip for that height is added to the zenith angle before it solves. Everything runs in your browser; no coordinate is sent anywhere.

Why do sunrise and sunset times shift so much through the year?

Earth's rotation axis is tilted about 23.4° relative to its orbit, so the Sun's declination swings from +23.4° at the June solstice to −23.4° in December. The higher the Sun climbs at noon, the longer the arc it traces above the horizon, so summer days are long and winter days short. The effect grows with latitude: near the equator day length barely changes, while above the Arctic and Antarctic circles the Sun can stay up or stay down for a full 24 hours.

What is civil twilight and the golden hour?

Civil twilight is the period when the Sun's centre is between the horizon and 6° below it; there is still enough scattered light to see and work outdoors without artificial lighting. Civil dawn is when it begins in the morning and civil dusk when it ends in the evening. The golden hour is the softer window when the Sun is low but above the horizon — this tool marks the evening golden hour as the moment the Sun descends back to 6° of elevation before setting.

What time is golden hour?

Golden hour has no fixed clock time — it is the window while the Sun's centre sits between about 4° below and 6° above the horizon, and it shifts every day with latitude and season. At mid-latitudes it typically spans 45–90 minutes around sunrise and again before sunset (London's evening window on the June solstice runs 20:27–21:50 BST, about 83 minutes); near the equator the Sun crosses the band at its steepest and the window bottoms out at about 40 minutes — the geometric minimum, since the Sun's altitude never changes faster than 15° per hour — while at high latitudes it can stretch for hours or, on some dates, not happen at all. Enter your coordinates and date above and the tool prints today's exact morning and evening windows on your local clock.

What is the blue hour?

The blue hour is the slice of twilight when the Sun's centre is between 6° and 4° below the horizon — just before the morning golden hour and just after the evening one. Direct sunlight is gone, but the upper atmosphere still scatters short blue wavelengths, giving an even, deep-blue ambient light that photographers use for cityscapes, architecture and long exposures because artificial lights balance naturally against the sky. Despite the name it is short: usually 15–40 minutes at mid-latitudes, and at very high latitudes there are dates with no blue hour at all — this tool states that plainly instead of showing a time.

What are nautical and astronomical twilight?

They are the two darker twilight bands below civil twilight, defined by how far the Sun's centre sits below the horizon. Civil twilight ends 6° down, when you can no longer read outdoors comfortably. Nautical twilight ends 12° down: it is named for celestial navigation, because down to that point the sea horizon is still a visible line against the sky, so a navigator can take a sextant sight on stars. Astronomical twilight ends 18° down; below that the Sun no longer measurably brightens the sky, which is the start of true darkness for deep-sky observing and astrophotography. The twilight table above prints the dawn and dusk crossing of all three bands. They do not always exist: London gets no astronomical twilight at all on the 60 nights from 23 May to 20 July 2026, because around the June solstice the Sun only sinks to about 15° below the horizon at solar midnight.

Why does day length change fastest near the equinox?

Because the Sun's declination — its angle north or south of the celestial equator — moves through the year like a sine wave. At the equinoxes that wave is at its steepest, changing about 0.4° per day, while at the solstices it is momentarily stationary, which is exactly why a solstice feels like weeks of unchanging day length. The effect is then amplified by latitude. In 2026 London's fastest gain is about 3 min 59 s of daylight per day, around 18 March; on 21 June the same city gains roughly 2 seconds. At the equator day length barely moves at all, staying within a few minutes of 12 hours all year. The Day length readout on this page shows today's daylight plus the signed change against yesterday, so you can watch that curve directly.

What is solar noon, and why is it not 12:00?

Solar noon is the instant the Sun is highest and due south (or due north in the Southern Hemisphere) — the true midpoint of the day. It rarely lands on 12:00 clock time for two reasons: your longitude may sit east or west of the meridian that defines your time zone, shifting noon earlier or later; and the equation of time, which comes from Earth's elliptical orbit and axial tilt, makes real solar time run up to about 16 minutes ahead of or behind clock time across the year.

How do I set the right UTC offset, including daylight saving?

Pick your zone from the Time zone list beside the date and the offset is filled in for you, resolved for the date in the Date field rather than for today. Europe/London reads UTC+00:00 on 15 January 2026 and UTC+01:00 (British Summer Time) on 21 June 2026; Australia/Sydney runs the other way, UTC+11:00 in January and UTC+10:00 in July. The resolved offset and the zone's own abbreviation are both printed above the control. That lookup uses your browser's copy of the IANA time-zone database through the built-in Intl API, so no zone data ships with this page and nothing is downloaded — which is also the honest limit: the answer is only as good as that copy, and a date years ahead is really today's rule projected forward, which governments do change. Nothing is applied behind your back. The UTC offset stays an ordinary editable field, changing it takes over and switches the picker to Set the offset by hand, and on a date when the clocks change the page says so on screen, naming the local hour a spring-forward jump deletes entirely.

Can I print a whole year of sunrise and sunset times for my town?

Yes. Enter the town (or its coordinates) and its time zone, set the Year field in The whole year section, and press Print table: the printout is the year chart plus twelve month tables of sunrise, sunset and day length on the local clock, four months across, on two A4 or Letter pages. Summer-time changes are applied on their real dates and marked in the table. Download CSV gives the same 365 rows (366 in a leap year) with solar noon, civil dawn and dusk and the UTC offset added, and the SVG and PNG downloads save the chart. Everything is computed in your browser; for years far ahead, the summer-time dates are today's rules projected forward.

Why is the earliest sunset not on the shortest day?

Because of the equation of time. At London the earliest sunset falls around 13 December, the shortest day is the solstice on 21 December, and the latest sunrise is not until about 31 December — the sequence is spread across roughly three weeks. The solstice is the shortest gap between sunrise and sunset, but the equation of time slides both events a little later through December, so sunset bottoms out before the solstice and sunrise keeps getting later after it. Run London through the calculator on those dates and you can watch it happen.

How do I find the horizon angle for the skyline fields?

Measure it, or read it off a map. The angle is arctan(height above you ÷ horizontal distance): a ridge whose top is 400 m higher than where you stand and 2 km away sits arctan(400/2000) = 11° above level, and a 30 m building 60 m down the street is arctan(30/60) = 27°. A phone clinometer app gives the same number in a second if you can see the skyline. Rough is fine: at London’s latitude on the equinox each extra degree of eastern skyline costs roughly 7 minutes near the horizon, so a degree of error is a few minutes, not an hour. Two limits, stated plainly: this is one angle per direction, not a profile of your whole skyline, so a jagged ridge, a notch or a gap between two buildings is still an approximation; and the sunrise azimuth moves through the year, so an angle measured in June may not be the part of the ridge the December Sun comes over. Leave both fields blank and the tool computes for a clean flat horizon exactly as it always did.

Does my elevation change sunrise and sunset times?

Yes, and this calculator models it. Height above sea level lowers your horizon by the dip angle — arccos(R/(R+h)), adjusted for the way low-level air bends the sight line — so the Sun clears it earlier and sets later. Enter a figure in the Your elevation field (metres or feet) and the times, the day length and an explicit “x min earlier than at sea level” label update immediately. The size of the gain depends on latitude and season as much as on height: 1,609 m at Denver advances sunrise about 7 minutes, while 1,345 m on Ben Nevis advances it about 12 minutes in June, because the midsummer Sun rises at a much shallower angle that far north. Solar noon and the twilight and golden-hour bands are not shifted — they are defined by the Sun's own altitude, which your height cannot change. Height is usually the smaller of the two horizon corrections, though: Denver's 1,609 m buys about 7 minutes, while 5° of eastern ridge costs about 35 minutes at London's latitude on the equinox — which is what the separate skyline fields are for.

How accurate are the times, and what are the limits?

For most locations the times are good to within about a minute of published almanac values. It is a clear-sky geometric model: it assumes a standard 0.833° refraction at the horizon, so unusual air temperature or pressure can shift the real sunrise by a minute or more. Your height above sea level is modelled if you enter it, and so is the terrain that actually blocks the view: put the angular height of your eastern and western skyline into the two skyline ° fields and the crossing is solved against that. The limit there is that it is one angle per direction rather than a profile of your whole skyline, so a jagged ridge is still an approximation — and you have to supply the angle, since the page holds no terrain data. Daylight saving is not guessed either: the optional zone picker reads your browser's own IANA time-zone data for the date you entered and fills in an offset you can still overrule, so it is as current as that browser rather than a table frozen into this page. And near the poles, on days the Sun does not cross the horizon, it reports polar night or midnight sun instead of a time.

Can I type a town name instead of latitude and longitude?

Yes. The "Town or city" box sits directly beside the coordinate field and searches 171,041 places from GeoNames — everywhere with 1,000 people or more, so small towns such as Skagen, Ebeltoft and Bad Tölz are found as well as cities. Pick a suggestion and it writes that town's latitude and longitude into the coordinate field, so the times you get are the same ones you would get by typing those numbers by hand. Accents are optional, and a country or a US state code narrows a common name: "Roskilde Denmark", "Roskilde, Denmark" and "Springfield MA" all resolve. Matching is exact rather than fuzzy, so a misspelling finds nothing instead of quietly finding the wrong town. The main list of 29,919 places of 18,000+ people is downloaded on your first keystroke in that box and never when the page loads; the other 141,122 smaller places come in slices of roughly 100–130 KB compressed, fetched only when the main list has no answer for the name you typed. If a small-town slice will not download, only those small towns go missing (the box then says no town of 18,000+ people matched, the most it can vouch for); if the main list will not download, the box disables itself and the coordinate field, the city buttons and "Use my location" keep working.

Do you upload my location?

No. Every calculation runs in JavaScript in your browser using a small vendored solar library committed alongside this page, and no coordinate you enter is sent anywhere. If you use the optional "Use my location" button the coordinates stay on your device and are only used to fill the input. One file is downloaded, and only if you ask for it: your first keystroke in the "Town or city" box fetches the town list, a static 715 KB file served from this same site. That transfer is one-way — it carries nothing about what you typed and there is no reply for it to send — and if you never use that box it is never requested. You can disconnect from the internet and the calculator keeps working from the coordinate field; only the town search needs that file.

const solar = require('@verifyhash/solar-calc');
const [lat, lon, day] = [51.5074, -0.1278, { year: 2026, month: 6, day: 21 }], hm = (t) => new Date(Math.round(t / 6e4) * 6e4).toISOString().slice(11, 16);
console.log(`sunrise ${hm(solar.sunrise(lat, lon, day))} UTC, sunset ${hm(solar.sunset(lat, lon, day))} UTC, ${(solar.dayLengthMinutes(lat, lon, day) / 60).toFixed(2)} h of daylight`);

sunrise 03:43 UTC, sunset 20:22 UTC, 16.64 h of daylight