Recipe converter

Every resize is one multiplication. Work out the factor once, then apply it to each ingredient:

factor = servings you want ÷ servings the recipe makes

A factor above 1 makes more, below 1 makes less. The servings scaler above does this for you one ingredient at a time and rounds cups and spoons to fractions you can measure.

Worked example: a recipe for 6, cooked for 4

4 ÷ 6 = ⅔, so every amount is multiplied by ⅔:

• 1½ cups rice × ⅔ = 1 cup
• 3 tablespoons olive oil × ⅔ = 2 tablespoons
• 1 pound chicken (454 g) × ⅔ = about 302 g, or just over ⅔ pound
• 3 cups stock × ⅔ = 2 cups

How to halve a recipe

Halving is a factor of 0.5. Most amounts split cleanly; the ones that don't are odd cup fractions and eggs. Use spoons for those: a cup is 16 tablespoons and a tablespoon is 3 teaspoons, so half of ⅓ cup is 2 tablespoons plus 2 teaspoons, and half of ¾ cup is 6 tablespoons.

Worked example: half a batch of cookies

• 2¼ cups flour → 1 cup plus 2 tablespoons
• ¾ cup sugar → 6 tablespoons
• 1 cup butter (2 sticks) → ½ cup (1 stick)
• 1 teaspoon baking soda → ½ teaspoon
• 2 large eggs → 1 egg

For one egg, beat it and use half by weight. USDA FoodData Central lists a large egg at 50 g without the shell, so half is about 25 g of beaten egg. Keep the oven temperature the same, use a smaller pan if the recipe bakes in one, and start checking for doneness earlier than the original time.

How to double a recipe

Doubling is a factor of 2. The ingredient math is the easy part; the pan and the pot are where doubled recipes go wrong.

• Pans: two 8 by 8 inch pans have 128 square inches of surface. A 9 by 13 inch pan has 117, so a doubled 8 by 8 batter is a little deeper in it and may need more time. The baking pan converter gives the exact multiplier for your pans.
• Pots: a doubled soup or stew takes longer to come to a simmer, and a crowded pan steams instead of browning. Brown meat in batches.
• Seasoning: double the salt and spices if the recipe is trusted, but taste before the last addition.
• Mixer bowls: a doubled dough can overfill a stand mixer. Two batches are often easier than one big one.

Recipe divider: by 3, by 4, or any number

A recipe divider is the same tool used in the other direction. To divide a recipe by 3, enter its servings as the original and a third of them as the servings you want. A recipe for 12 cooked for 4 is a factor of ⅓:

• 2 cups flour → ⅔ cup
• 3 eggs → 1 egg
• 1 tablespoon baking powder → 1 teaspoon
• ¾ cup milk → ¼ cup

Dividing by 4 is a factor of ¼: 1 cup becomes ¼ cup, 1 tablespoon becomes ¾ teaspoon. When a divided amount lands on something you cannot measure, such as ⅙ teaspoon, round to the nearest spoon you own and write down what you did.

Recipe multiplier: scale by any factor

Every resize is one multiplication. The scaling factor is the servings you want divided by the servings the recipe makes: a recipe for 4 cooked for 10 has a factor of 10 ÷ 4 = 2.5, so 1 cup becomes 2½ cups and 2 eggs become 5. Enter the original and desired servings above and the scaler does the division for you, one ingredient at a time.

When the reason for scaling is a different pan rather than a different number of people, the baking pan converter gives the factor from the two pans' sizes. Weights make any factor easier: the cups to grams converter turns a recipe's cups into grams first.

Halve, double and divide at a glance

1 cup = 16 tablespoons = 48 teaspoons (NIST Handbook 44, Appendix C). Large egg weight from USDA FoodData Central (FDC 171287).

Serving size scaling: what does not follow the math

The multiplication is exact. Cooking is not always linear, so check these whenever the factor is far from 1:

• Eggs come whole. Round to the nearest egg, or beat and weigh for part of one.
• Cooking time and pan size follow depth and volume, not the ingredient list. Keep the temperature and check doneness by look, touch or thermometer.
• Evaporation depends on the pot's surface. A halved sauce in the same wide pan reduces faster.
• Leavening, salt and strong spices are small amounts where rounding matters most. Measure them carefully, or weigh.

If you scale a family recipe often, write the scaled version on its own card next to the original, with the date and what worked. Next time there is nothing to calculate.