Doubling a recipe is easy; turning a 4-serving recipe into 6, or a 12-serving cake into 3, takes arithmetic most of us don't want to do mid-cook. This recipe scale calculator finds the scale factor from the servings and multiplies up to six ingredient amounts at once, rounding each result to a fraction you can actually measure with standard cups and spoons.
How to use the recipe scale calculator
- Enter how many servings the recipe makes and how many you want.
- Enter the amounts of up to six ingredients as numbers — 0.75 for ¾, 1.5 for 1½. The unit stays the same, so ¾ cup scales to cups and 2 tsp scales to teaspoons.
- Read the scaled amounts next to each ingredient number.
Have more than six ingredients? Note the scale factor and multiply the rest, or run the calculator again.
Recipe scaling formula
New amount = original amount × scale factor
Results are rounded to the nearest ⅛ or ⅓ — the fractions on standard US measuring cups and spoons.
Worked example: 4 servings to 6
Scale factor: 6 ÷ 4 = 1.5
- 2 cups broth → 2 × 1.5 = 3 cups
- ¾ cup rice → 0.75 × 1.5 = 1.125 = 1⅛ cups
- 1 tsp salt → 1½ tsp
- ½ cup cheese → ¾ cup
Common scale factors
| Original amount | × ½ | × ⅔ | × 1½ | × 2 | × 3 |
|---|---|---|---|---|---|
| ¼ cup | ⅛ cup | 2 Tbsp + 2 tsp | ⅜ cup (6 Tbsp) | ½ cup | ¾ cup |
| ⅓ cup | 2 Tbsp + 2 tsp | 3 Tbsp + 1⅔ tsp | ½ cup | ⅔ cup | 1 cup |
| ½ cup | ¼ cup | ⅓ cup | ¾ cup | 1 cup | 1½ cups |
| ¾ cup | ⅜ cup (6 Tbsp) | ½ cup | 1⅛ cups | 1½ cups | 2¼ cups |
| 1 cup | ½ cup | ⅔ cup | 1½ cups | 2 cups | 3 cups |
When scaling doesn't work perfectly
Most stews, soups, sauces and salads scale smoothly. Baked goods are more sensitive: leavening, salt and spices don't always need the full multiplied amount in very large batches, and cooking times change with pan size and depth. Yeast doughs scale well by weight. Deep-fried or pan-seared recipes are limited by pan size more than ingredients — cook in batches rather than crowding the pan. When scaling a recipe down a lot, small amounts become hard to measure, so round sensibly and taste as you go.
Tips for scaling recipes
- Convert awkward amounts. 0.375 cup is 6 tablespoons — easier than eyeballing ⅜ cup. The Cooking Conversion Calculator converts cups, spoons and grams.
- Weigh when you can. Scaling grams is exact; scaling cups of flour compounds measuring errors.
- Adjust pans, not just ingredients. A doubled cake needs twice the pan area, not a deeper pan.
- Eggs: round to the nearest whole egg, or beat and measure — a large egg is roughly 3¼ tablespoons.
Frequently asked questions
How do I scale a recipe?
Divide the servings you want by the servings the recipe makes to get a scale factor, then multiply every ingredient by it. To turn a 4-serving recipe into 6 servings, the factor is 6 ÷ 4 = 1.5, so ¾ cup becomes 1⅛ cups.
How do I cut a recipe in half?
Use a factor of 0.5: set “recipe makes” to the original servings and “you want” to half. Halving an egg is easiest by beating it and measuring out half (about 2 tablespoons of a large egg).
Do I scale baking time too?
Not by the same factor. Baking time depends on the depth of the batter, not the total amount. If you use a bigger pan at the same depth, time stays similar; a deeper pan needs longer at the same or a slightly lower temperature. Check doneness early.
Can I scale spices and salt directly?
Usually, but when multiplying a recipe by a large factor, many cooks add spices, salt and leavening a little under the full amount at first, then adjust to taste.
Why are results shown as fractions?
Measuring cups and spoons come in fractions — ¼, ⅓, ½, ¾ — so the calculator rounds each amount to the nearest 1/8 or 1/3, whichever is closer, to make it easy to measure.