Scale a recipe to any number of servings: each ingredient is multiplied by new ÷ original servings, with cups and spoons shown as kitchen fractions.
By AdminDrafted with AI writing toolsUpdated Checked examples: 5
Servings: 4 → 6. Multiplier: 1.5. Lines with an amount: 6 of 6.
| Ingredient | Original | Scaled | Exact |
|---|---|---|---|
| cups flour | 2 | 3 | 3 |
| tsp salt | 1 1/2 | 2 1/4 | 2.25 |
| cup sugar | 3/4 | 1 1/8 | 1.125 |
| eggs | 2 | 3 | 3 |
| cup milk | 1/3 | 1/2 | 0.5 |
| g butter | 250 | 375 | 375 |
In the formula, q_1 and q_2 are the original and adjusted ingredient amounts; n_1 and n_2 are the original and required servings. Ingredient names and units stay as entered.
Shown as 3.
Cups, spoons and counts are rounded to the nearest kitchen fraction (eighths, quarters, thirds, halves); ≈ marks a rounded value. Grams, kilograms, millilitres and litres are shown as decimals to 2 places.
Every amount is multiplied by the scale factor: the servings you need divided by the servings the recipe makes. Cup, spoon and count amounts are rounded to the nearest measure a kitchen set holds (eighths, quarters, thirds and halves) and marked ≈ when rounded. Grams, kilograms, millilitres and litres stay as decimals.
The default recipe goes from 4 to 6 servings, a factor of 1.5, so 3/4 cup of sugar becomes 1 1/8 cups and 250 g of butter becomes 375 g. The Institute of Child Nutrition teaches the same two steps for school kitchens: 35 servings from a 25-serving recipe is a factor of 1.4, which turns 3 cups of tomatoes into 4.2 cups, rounded to 4 1/4.
Lines without a number, such as "salt to taste", are kept as written. Baking time, pan size and seasoning do not scale in proportion, so check them separately.
Divide the servings you need by the servings the recipe makes, and multiply every ingredient by that factor. For 30 cookies from a 12-cookie recipe, the factor is 30 ÷ 12 = 2.5: 2 cups of flour becomes 5 cups and 3/4 cup of sugar 1 7/8 cups.
Both numbers must count the same thing: servings of the same size, cookies, muffins or loaves. Four small portions and six large ones are not a factor of 1.5.
In US measures, 1 cup holds 16 tablespoons and 1 tablespoon holds 3 teaspoons. That turns any cup fraction into spoons:
Halving 1/3 cup gives 1/6 cup, which no cup measure holds. Kitchen-fraction rounding gives ≈ 1/8 cup, the nearest common measure, while 2 tbsp + 2 tsp measures 1/6 cup exactly.
Decimals work the same way. The Institute of Child Nutrition scales 3 cups of tomatoes by 1.4 (35 servings from 25) to 4.2 cups: 4 cups + 3 tbsp + about ½ tsp. Rounding to ≈ 4 1/4 cups adds 2.4 tsp.
NIST's culinary measurement tips recommend weighing ingredients, and a scale measures 93.75 g, three-quarters of 125 g, as easily as a round number. The cooking converter turns cups of flour, sugar or butter into grams.
Pan size. A bigger batch needs proportionally more pan area to bake at the same depth. A doubled 8-inch square recipe (64 sq in) needs 128 sq in: two 8-inch square pans, or a 9 × 13 pan (117 sq in) with a layer about 9% deeper.
The oven temperature and pan size converter gives the area factor between any round, square or rectangular pans.
Baking time. Time follows the depth of the batter more than its amount, so check for doneness early whenever the depth changes.
Leavening and strong seasoning. Over a large factor these don't always scale in proportion. Treat the scaled amount as a starting point and taste as you cook.
| Scenario | Scale factor | Lines scaled | Lines kept |
|---|---|---|---|
| Default | 1.500000 | 6.000000 | 0.000000 |
| Halving | 0.500000 | 3.000000 | 0.000000 |
| Unicode and range | 0.833333 | 3.000000 | 1.000000 |
| 35 servings from 25 | 1.400000 | 1.000000 | 0.000000 |
| Metric decimal | 0.750000 | 2.000000 | 0.000000 |
2 cups flour, 1 1/2 tsp salt, 3/4 cup sugar, ½ cup milk or 1.5 L stock. A leading range such as 2-3 cloves garlic scales both ends.3 x 400 g cans tomatoes correctly becomes 4 1/2 x 400 g cans, but 1 lb 8 oz butter becomes 1 1/2 lb 8 oz, so write 1.5 lb butter.1. before pasting, or it is read as the amount.salt to taste, are kept as written.Checked against: 2×3/2 = 3, 3/2×3/2 = 9/4, 3/4×3/2 = 9/8, 1/3×3/2 = 1/2, 250×3/2 = 375
Checked against: Each amount × 1/2
Checked against: 3/2×5/6 = 5/4; 2×5/6 = 5/3, 3×5/6 = 5/2; 5/6 = 0.833 is nearest 7/8 among eighths and thirds
Checked against: Institute of Child Nutrition, Adjusting Standardized Recipes: 35 ÷ 25 = 1.4; 3 cups × 1.4 = 4.2 cups, rounded to 4 ¼ cups
Divide the servings you need by the servings the recipe makes, then multiply every ingredient by that factor. Going from 4 to 6 servings is a factor of 1.5, so 2 cups of flour becomes 3 cups; going from 4 to 2 is 0.5. The Institute of Child Nutrition advises converting mixed amounts such as 1 lb 8 oz to one unit (1.5 lb) before multiplying.
Half of 1/3 cup is 1/6 cup: 2 tablespoons plus 2 teaspoons, because a US cup holds 16 tablespoons and a tablespoon holds 3 teaspoons. Half of 3/4 cup is 3/8 cup, or 6 tablespoons. When no standard measure matches, the calculator shows the nearest eighth or third with ≈ and gives the exact decimal in the table.
Often, because baking time depends on the depth of the batter more than on its amount. Doubled batter in the same pan is twice as deep and needs longer; spread over a pan with twice the area, it keeps its depth and bakes in close to the original time. Keep the oven temperature the same and test for doneness early.
No. A US customary cup is 8 US fluid ounces, 236.6 mL, while the metric cup used in Australia and New Zealand is 250 mL, about 6% larger. Scaling works the same in both systems because every amount is multiplied by the same factor. NIST advises weighing ingredients on a kitchen scale for accuracy rather than measuring by volume.
This calculator includes 5 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.