Recipe Scaler: How to Scale a Recipe Up or Down

To scale a recipe, divide the number of servings you want by the number of servings the recipe makes, then multiply every ingredient by that scaling factor. A recipe for 4 that you need for 6 has a factor of 1.5, so 2 cups of flour becomes 3 cups and 2 eggs become 3.

The math is simple, but doing it line by line with fractions is where mistakes creep in. The free recipe scaler calculates the factor and rewrites your ingredient list for the new serving count, showing results as kitchen fractions.

This guide shows the formula, a full worked example, the parts of a recipe that don't scale in a straight line, and how to handle awkward amounts like a third of an egg.

How to scale a recipe: the formula

scaling factor = desired servings ÷ original servings
new amount     = original amount × scaling factor

A factor above 1 scales the recipe up and a factor below 1 scales it down. Doubling is a factor of 2, halving is 0.5, and turning a recipe for 8 into one for 2 is 0.25.

Worked example: pancakes for 4 scaled to 6

The scaling factor is 6 ÷ 4 = 1.5. Multiply each line, then convert any awkward result into a measure you can actually use.

Notice the last column. A scaled amount is only useful if your measuring cups and spoons can hold it, which is why knowing a few equivalents saves time.

Kitchen equivalents for awkward scaled amounts

Why scaling by weight is easier

Grams and milliliters scale cleanly. Multiplying 75 g of sugar by 1.5 gives 112.5 g, which a scale measures exactly. Multiplying 3/8 cup by 1.5 gives 9/16 cup, which no measuring cup holds.

If you bake often, convert the recipe to weights once with the cooking converter, then scale the gram amounts. Our guide to converting cups to grams explains why the same cup weighs differently for flour, sugar and butter.

What doesn't scale in a straight line

Ingredient amounts scale by the factor. Several other parts of a recipe do not.

• Pan size. Doubling a cake recipe means a pan with twice the volume, or two pans, not the same pan filled twice as deep. The baking pan converter compares pan volumes for you.
• Baking time. Time depends on how deep the batter or dough is, not how much of it there is. Two pans of the original size bake in about the original time; one deeper pan takes longer.
• Oven temperature. Keep the original temperature in almost every case.
• Stovetop time. A bigger pot of soup takes longer to come to a boil, and a sauce in a wider pan reduces faster. Cook to the visual cue in the recipe, not the clock.
• Seasoning. When scaling up a lot, many cooks add salt and strong spices at slightly less than the full factor, then taste and adjust at the end.
• Equipment capacity. A tripled batch may not fit your mixer, pot or skillet. Cooking in two batches often works better than crowding one pan.

Scaling eggs

Eggs are the most common awkward ingredient. Round to the nearest whole egg in forgiving recipes like pancakes or meatballs. For cakes and custards, beat the egg and measure by weight: a large egg out of the shell weighs about 50 g, so half an egg is about 25 g and a quarter is about 12 g.

How to use the Recipe Scaler

1. Open the Recipe Scaler and enter the number of servings the recipe makes in Original Servings.
2. Enter the number you want in Desired Servings. Decimals are accepted, and the Scaling factor updates as you type.
3. Paste your ingredients into the Ingredients box, one per line, with the amount in front of the unit, for example 2 cups flour or 250 g sugar.
4. Read the Scaled Recipe panel, which lists each line at the new amount. Results close to a kitchen fraction are written as one, such as 1 1/2 or 2/3, and anything else as a decimal.
5. Check any amount in the middle of a line. The amount a line starts with is always scaled, so 2 eggs becomes 3 eggs at a factor of 1.5. A later amount, as in 2 cups (250 g) flour, is scaled only when a whole-word unit follows it: cups, tablespoons (tbsp), teaspoons (tsp), pounds (lb), ounces (oz), grams (g), kilograms (kg), milliliters (ml) or liters (l), with millilitres and litres spelled either way. A package size is left alone, so 1 (14 oz) can or 1 x 400g tin doubles to 2 cans of the same size.

You can also use the tool to apply any multiplier, not just servings. Set Original Servings to 1 and Desired Servings to the factor, such as 1.27 from a pan size calculation.

Tips for scaling recipes without surprises

• Check the serving size, not just the count. A recipe that "serves 4" may assume small portions. Scale from how many people it actually fed you.
• Paste amounts as the recipe writes them. Whole numbers, fractions such as 1 1/2, decimals such as 0.75 and characters such as ½ all scale.
• Scale bread by baker's percentages. For dough, it is more reliable to work from flour weight. See our guide to baker's percentages and dough hydration.
• Measure leavening carefully. Baking powder and soda scale with the batter, but rounding them up generously can leave a bitter or soapy taste.
• Write the scaled recipe down. Mid-recipe is the worst time to recalculate, and it is easy to scale one ingredient twice or not at all.

Frequently asked questions

How do you calculate a recipe scaling factor?

Divide the servings you want by the servings the recipe makes. For a recipe that serves 4 when you need 10, the factor is 10 ÷ 4 = 2.5, and every ingredient is multiplied by 2.5.

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

No. Baking time depends on the depth of the batter and the pan, not the total amount. If you bake a doubled recipe in two pans of the original size, the time stays about the same; in one larger, deeper pan it will take longer, so start checking at the original time.

How do I halve a recipe that calls for 3 eggs?

Use 1 whole egg plus half of a second one. Beat the second egg and measure about 25 g, which is half of a large egg without the shell.

Can you scale any recipe up or down?

Most everyday recipes handle halving, doubling and tripling well. The bigger the change, the more pan size, cooking time, evaporation and equipment capacity matter, so expect to adjust those by eye.

How many tablespoons are in 1/3 cup?

One-third of a US cup is 5 tablespoons plus 1 teaspoon. That is a handy equivalent when you scale 1 cup down by a factor of one-third.

Should I scale salt and spices exactly?

For small changes, yes. For large batches, many cooks add seasoning at slightly less than the full factor and finish by tasting, since it is easier to add salt than to remove it.