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Formula
Scale factor = new servings ÷ original servings; new amount = original amount × scale factor
- scale factor
- how many times larger (above 1) or smaller (below 1) the new batch is
- original amount
- the quantity of an ingredient in the recipe as written
- new amount
- the quantity to use in the scaled recipe
What the recipe scaler does
Recipes are written for a set number of servings, and the number you need is rarely the same. Doubling is easy in your head; turning a 6-serving recipe into 10 servings is not, and the results land on amounts like 1.667 cups or 3.333 tablespoons that no measuring cup has.
This recipe scaler handles both steps. It works out the scale factor, multiplies every ingredient, and then rewrites each amount in a measure you can use:
- Scale factor, as a multiplier and a percentage.
- The exact scaled amount for each ingredient.
- A kitchen measure, such as 1¼ cups, 3 tbsp + 1 tsp, 1 lb 4 oz or 150 g.
How to use the recipe scaler
- Choose By servings if you know how many people the recipe feeds, or By factor to double, halve or apply any other multiplier.
- Enter the servings the recipe makes and the servings you need, or the factor.
- For each ingredient, enter the amount as a decimal (0.75 for ¾) and pick its unit: cups, tablespoons, teaspoons, fluid ounces, milliliters, liters, ounces, pounds, grams, kilograms or whole items.
- Leave unused ingredient rows empty. The results table shows original, exact and practical amounts side by side.
The recipe scaling formula
Scaling is a simple proportion:
scale factor = new servings ÷ original servings
new amount = original amount × scale factor
The maths is the easy part. The useful part is converting the answer into real measures. US kitchen units fit together neatly: 1 cup = 16 tablespoons, 1 tablespoon = 3 teaspoons, and 1 fluid ounce = 2 tablespoons. NIST lists the matching metric equivalents as about 240 mL per cup, 15 mL per tablespoon and 5 mL per teaspoon.
Scaling a recipe by hand
A stew serves 6 and you need 10.
- Scale factor: 10 ÷ 6 = 1.667.
- ¾ cup of flour × 1.667 = 1.25 cups, which is 1¼ cups.
- 2 tbsp of butter × 1.667 = 3.33 tbsp. Convert to teaspoons: 3.33 × 3 = 10 tsp, or 3 tbsp + 1 tsp.
- 3 eggs × 1.667 = 5 eggs.
Scaling baking recipes
Baking is less forgiving than stews and soups, because the ratios between flour, liquid, fat and leavening decide the texture. Scaling every ingredient by the same factor keeps those ratios intact, which is exactly what the recipe scaler does. The risk comes from rounding: a few grams of salt or baking soda are a larger share of the total than a few grams of flour. For baking, weigh ingredients where you can, keep the exact scaled amount for small quantities, and use a pan whose area changes by roughly the same factor as the recipe so the batter stays at the same depth.
Awkward amounts and what to measure
These are kitchen measures the calculator produces for common scaling results.
| Original × factor | Exact result | Measure it as |
|---|---|---|
| ¾ cup × ½ | 0.375 cup | 6 tbsp |
| ⅓ cup × ½ | 0.167 cup | 2 tbsp + 2 tsp |
| ¼ cup × ½ | 0.125 cup | 2 tbsp |
| ⅓ cup × 1.5 | 0.5 cup | ½ cup |
| ¾ cup × 1.5 | 1.125 cups | 1 cup + 2 tbsp |
| ⅓ cup × 2.5 | 0.833 cup | ¾ cup + 1 tbsp + 1 tsp |
| 1½ tsp × 2.5 | 3.75 tsp | 1 tbsp + ¾ tsp |
| 1 tsp × ⅓ | 0.333 tsp | ⅜ tsp (nearest ⅛) |
Where scaling helps
- Feeding a crowd. Scale a family recipe up for a party; for large batches, weigh dry ingredients with the cups to grams converter.
- Cooking for one or two. Halve or third a recipe without guessing at spoon amounts.
- Fitting your pan. Scale by the ratio of pan areas, for example ×1.78 to go from a 9-inch to a 12-inch round.
- Switching units. Convert scaled metric amounts with the volume converter or the weight converter.
Common mistakes
- Scaling the cooking time. Twice the batter does not mean twice the time. Time depends on depth and pan size, so check early.
- Scaling leavening blindly in big jumps. Baking powder, yeast and salt usually scale fine for doubling, but for very large or very small batches taste and test, because small rounding errors matter more.
- Rounding everything to the nearest cup. Rounding 1⅓ cups down to 1 cup is a 25% cut. Use the spoon breakdown instead.
- Mixing up fluid ounces and ounces. Fluid ounces measure volume, ounces measure weight. Only for water-like liquids are they close.
- Forgetting seasoning is personal. Scale spices and salt, then adjust to taste near the end.
Glossary
- Scale factor. The multiplier applied to every ingredient.
- Yield. How much a recipe makes, in servings, pieces or weight.
- Baker’s percentage. Ingredients expressed as a percentage of flour weight, which scale without any conversion.
- Pinch. A tiny amount, conventionally less than ⅛ teaspoon.
Worked examples
Four servings up to six
A 4-serving recipe with ¼ cup oil, 1 tsp salt and 2 eggs, scaled for 6 people. ¼ cup becomes 6 tbsp.
Inputs (By servings): Recipe makes = 4 servings; You need = 6 servings; Ingredient 1 amount = 0.25; Ingredient 1 unit = cups; Ingredient 2 amount = 1; Ingredient 2 unit = teaspoons; Ingredient 3 amount = 2; Ingredient 3 unit = whole items (eggs, cloves…)
Scale factor = new servings ÷ original servings = 6 ÷ 4 servings = 1.5 Ingredient 1: 0.25 cup × 1.5 = 0.375 cup ≈ 6 tbsp Ingredient 2: 1 tsp × 1.5 = 1.5 tsp ≈ 1½ tsp Ingredient 3: 2 × 1.5 = 3 ≈ 3
Answer: Multiply each ingredient by 1.5: 0.25 cup → 6 tbsp; 1 tsp → 1½ tsp; 2 → 3.
Twelve muffins down to eight
A 12-muffin batch (2 cups flour, ¾ cup sugar, 1½ tsp baking powder, 225 g butter) cut to 8 muffins.
Inputs (By servings): Recipe makes = 12 servings; You need = 8 servings; Ingredient 1 amount = 2; Ingredient 1 unit = cups; Ingredient 2 amount = 0.75; Ingredient 2 unit = cups; Ingredient 3 amount = 1.5; Ingredient 3 unit = teaspoons; Ingredient 4 amount = 225; Ingredient 4 unit = grams
Scale factor = new servings ÷ original servings = 8 ÷ 12 servings = 0.6667 Ingredient 1: 2 cup × 0.6667 = 1.333 cup ≈ 1⅓ cups Ingredient 2: 0.75 cup × 0.6667 = 0.5 cup ≈ ½ cup Ingredient 3: 1.5 tsp × 0.6667 = 1 tsp ≈ 1 tsp Ingredient 4: 225 g × 0.6667 = 150 g ≈ 150 g
Answer: Multiply each ingredient by 0.6667: 2 cup → 1⅓ cups; 0.75 cup → ½ cup; 1.5 tsp → 1 tsp; 225 g → 150 g.
Halving a recipe by factor
Half of ¾ cup milk, 1 tbsp butter and 1 lb ground beef.
Inputs (By factor): Scale factor = ×0.5; Ingredient 1 amount = 0.75; Ingredient 1 unit = cups; Ingredient 2 amount = 1; Ingredient 2 unit = tablespoons; Ingredient 3 amount = 1; Ingredient 3 unit = pounds
Scale factor = 0.5 Ingredient 1: 0.75 cup × 0.5 = 0.375 cup ≈ 6 tbsp Ingredient 2: 1 tbsp × 0.5 = 0.5 tbsp ≈ 1½ tsp Ingredient 3: 1 lb × 0.5 = 0.5 lb ≈ 8 oz
Answer: Multiply each ingredient by 0.5: 0.75 cup → 6 tbsp; 1 tbsp → 1½ tsp; 1 lb → 8 oz.
Edge case: tripling a pinch-sized amount
Tripling ⅛ tsp of cayenne gives ⅜ tsp, shown to the nearest eighth of a teaspoon.
Inputs (By factor): Scale factor = ×3; Ingredient 1 amount = 0.125; Ingredient 1 unit = teaspoons
Scale factor = 3 Ingredient 1: 0.125 tsp × 3 = 0.375 tsp ≈ ⅜ tsp
Answer: Multiply each ingredient by 3: 0.125 tsp → ⅜ tsp.
Assumptions and limitations
- Every ingredient is scaled by the same factor. US kitchen measures are used: 1 cup = 16 tbsp = 48 tsp, 1 tbsp = 3 tsp and 1 fl oz = 2 tbsp.
- Volumes of ¼ cup or more are shown in ¼ or ⅓ cup steps when within 2%; below ½ cup they may be shown as whole tablespoons; otherwise as cups plus spoons. Smaller amounts are rounded to the nearest ⅛ teaspoon, and anything under 1/16 tsp shows as a pinch.
- Ounces and pounds are shown to the nearest ¼ oz. Grams and milliliters are rounded to 0.5 under 10, to whole numbers under 100, and to the nearest 5 above that.
- Whole items such as eggs are shown to the nearest quarter, with the nearest whole number suggested when the result is fractional.
- The exact scaled amount is always shown next to the rounded kitchen measure.
- Cooking times, pan sizes and oven temperatures are not scaled. Large changes (more than ×4 or less than ×¼) trigger a reminder to check them.
Frequently asked questions
How do you scale a recipe?
Divide the servings you want by the servings the recipe makes to get the scale factor, then multiply every ingredient by it. Going from 6 servings to 10 gives 10 ÷ 6 ≈ 1.667, so ¾ cup of flour becomes 1¼ cups.
How do I scale a recipe down?
Use a factor below 1. Halving uses 0.5 and two-thirds uses 0.667. Small amounts get awkward fast, so convert them to spoons; for example, half of ⅓ cup is 2 tbsp + 2 tsp.
What is a recipe scale factor?
It is the number you multiply each ingredient by. A factor of 2 doubles the recipe, 0.5 halves it, and 1.5 makes it half again as large. The calculator shows it as, for example, ×1.5 and as a percentage.
How do I scale eggs in a recipe?
Scale them like any ingredient, then round sensibly. If you need 2½ eggs, beat 3 eggs and use about five-sixths of the mix, or use 2 large eggs plus a tablespoon or two of beaten egg. In forgiving recipes, rounding to the nearest whole egg is fine.
Do I need to change the baking time when I scale a recipe?
Often, yes. Baking time depends on the depth of the batter or dough, not the amount. A doubled cake in a larger pan of the same depth bakes in about the same time; in a deeper pan it takes longer. Check doneness early and adjust.
Is it better to scale by weight or volume?
Weight is more precise, especially for flour and sugar, because a cup can hold different amounts depending on how it is filled. If your recipe lists grams, scale the grams; if not, a cups to grams converter can help you switch.
Sources
- Metric Kitchen: Cooking Measurement Equivalencies — National Institute of Standards and Technology (NIST). Checked October 10, 2026.