Recipe Scaler

How to scale a recipe

1. Paste the recipe: the ingredient list, the steps, a "Serves 4" line. A recipe copied from a web page or a note on your phone is fine.
2. Choose how to scale. By factor: 2 doubles, 0.5 halves, 1/3 or 1 1/2 work too. By servings: the recipe's servings and yours (4 to 6 is × 1.5). By pan size: the recipe's pan and yours.
3. Read the result on the right. Changed amounts are highlighted; every line that was left alone says why. Copy it, print it, or save it on this device.

Only the amount at the start of a line is scaled, plus a measure in brackets just after it: "2 cups (250 g) flour" × 1.5 becomes "3 cups (375 g) flour". A can size in brackets before the unit is kept: "1 (14 oz) can condensed milk" × 2 becomes "2 (14 oz) cans". Numbers inside steps ("divide into 2 loaves") are not touched, because the scaler cannot tell an amount from a count of tins or a cutting instruction.

It reads whole numbers, decimals (1.5 or 1,5), fractions (3/4), unicode fractions (½, ¾, ⅓), mixed numbers (1 1/2, 1-1/2, 1 ½), ranges (2-3, 2–3, 2 to 3) and the words one to twelve, with cups, tablespoons (tbsp, T), teaspoons (tsp, t), fl oz, pints, quarts, ml, cl, dl, litres, g, kg, oz, lb and sticks of butter, spelled out or abbreviated.

How the amounts are written

Kitchen fractions round cups and spoons to the nearest ⅛, which is what a set of measuring cups and spoons can measure; cups also allow ⅓ and ⅔. So ¾ cup × 1.5 = 1.125 cups is written "1 ⅛ cups", and ⅓ cup × 2 is "⅔ cup", not 0.67. Ounces round to the nearest ¼, counts (eggs, cloves, onions) to the nearest ¼ or ⅓. Grams and millilitres are always decimals, whole numbers from 10 up. Choose Decimals if you would rather see 1.13 cups and weigh or measure it yourself.

Eggs. When the scaled count is not whole, a note under the line says how to measure it: 2 eggs × 1.25 = 2.5 eggs, "beat 3 and use 5/6 of it (about 125 g)". A large egg is 50 g out of the shell (USDA FDC 171287), so weighing the beaten egg is the easiest way.

Scaling by pan size

A pan is scaled by the area of its base, so the batter stands at the same depth as in the original recipe. An 8-inch round pan has π × 4 × 4 = 50.3 sq in; a 9 × 13 pan has 117 sq in; the recipe is multiplied by 117 / 50.3 = 2.33. Pans are measured across the top inside edge; sloped sides and rounded corners make the real volume a few percent smaller than the area suggests.

Bake times and temperatures do not scale

Bake times and temperatures do not scale linearly, so the scaler never changes them: any line with a temperature (350°F, 180 °C, gas mark 4) or a time (25 minutes, 1 hour) is left exactly as written and marked. The oven temperature stays the same. The time depends on how thick the food is in the pan, not on how much is in the bowl: a doubled batch of cookies on the same trays bakes in the same time per tray, while a cake in a deeper or larger pan can take 25 to 50 percent longer and may want 10 to 15 °C (25 °F) less so the edges do not overbake. Start checking at the original time.

Cups to grams

Weighing beats measuring by volume: a cup of flour spooned into the cup and levelled weighs about 125 g, the same cup scooped from the bag can weigh 140 g or more. The weights here are the portion weights published by USDA FoodData Central (SR Legacy, public domain), one food at a time, each with its FDC number. Grams for ingredients not on this list are not guessed: the line keeps its cups and says so. "1 cup almond flour" or "1 cup coconut milk" stays in cups, because almond flour is not wheat flour and coconut milk is not milk.

A plain name is read as the most common kind: "flour" as all-purpose flour, "sugar" as granulated, "milk" as whole milk, "butter" as salted butter, "brown sugar" as packed. The line's tag names the food and FDC number used, so you can see what it assumed. Measures are US: 1 cup = 236.6 ml, 1 tbsp = 14.8 ml, 1 tsp = 4.9 ml. An Australian cup is 250 ml and an Australian tablespoon 20 ml, so recipes written with those come out a little low.

What it cannot do

• Bake times and temperatures do not scale linearly and are never changed (see above). Neither is pan depth.
• It does not read a photo of a recipe or fetch a web link: copy the text and paste it.
• Grams only for the 51 ingredients in the table; anything else is not guessed.
• Only amounts at the start of a line are scaled. "Salt and pepper to taste" or "a pinch of salt" are left as is and marked.
• Leavening, salt and spices do not always scale well past 3× or 4×; yeast doughs and big batches may need less than the straight multiple. It cannot judge that for you.
• Up to 200 lines; anything after line 200 is not shown.

Privacy and what is stored

Your recipe never leaves your device; all the scaling happens in this page. As you type, the recipe in the box is kept in this browser's local storage so a reload does not lose it, and recipes you save are kept there too. Clear everything saved deletes all of it in one tap. The page sends an anonymous page-view count and, at most, two fixed words (recipe-scale, recipe-grams); never any of your text.

Questions

How do I scale a recipe from 4 servings to 6?

Divide the servings you want by the servings the recipe makes: 6 / 4 = 1.5, then multiply every ingredient by 1.5. 3/4 cup of milk becomes 1 ⅛ cups, 2 tbsp of sugar becomes 3 tbsp, and 2 eggs become 3. Paste the recipe here, choose By servings and type 4 and 6, and every line is done at once.

How do I convert a recipe from an 8-inch round pan to a 9x13 pan?

Compare the pan areas. An 8-inch round pan is π × 4 × 4 = 50.3 square inches; a 9 × 13 pan is 117 square inches, so multiply the recipe by 117 / 50.3 = 2.33 to fill the bigger pan to the same depth. Check for doneness early and often: a different pan shape bakes differently, so the time is not simply scaled.

How many grams is a cup of all-purpose flour?

USDA FoodData Central gives 125 g for 1 cup of all-purpose flour (FDC 168894). How you fill the cup matters: spooned in and levelled lands near that figure; scooped straight from the bag packs it and can weigh 140 g or more, which is why bakers who want the same result every time weigh flour.

Do you double the baking time when you double a recipe?

No. Oven temperature stays the same, and baking time depends on the depth and size of what is in the pan, not on the amount of batter in the bowl. Cookies baked on the same trays take the same time; a cake baked in a deeper pan takes longer, often 25 to 50 percent, and may need a slightly lower temperature so the outside does not burn. Start checking at the original time.

How do I halve a recipe with 3 eggs?

Half of 3 eggs is 1 ½ eggs. Use one whole egg, then beat a second egg and use half of it, about 25 g, since a large egg is about 50 g out of the shell (USDA FDC 171287). The scaler writes this note for you whenever the scaled egg count is not whole.