Recipe Scaling Calculator
Enter how many servings the recipe makes, how many you want, and each ingredient with its amount. The calculator finds the scale factor — servings wanted divided by servings in the recipe — and multiplies every amount by it.
Answer
Scale every amount by
×1.5
6 ÷ 4 servings — use more of everything.
| Ingredient | For 4 | For 6 |
|---|---|---|
| Flour | 250 g | 375 g |
| Milk | 300 ml | 450 ml |
| Eggs | 2 | 3 |
| Butter | 40 g | 60 g |
Check the work
Every line comes from the same calculation as the answer.
new amount = amount × (servings wanted ÷ recipe servings)
| factor | 6 ÷ 4 | 1.5 |
|---|---|---|
| flour | 250 g × 1.5 | 375 g |
| milk | 300 ml × 1.5 | 450 ml |
| eggs | 2 × 1.5 | 3 |
| butter | 40 g × 1.5 | 60 g |
How it works
Scaling a recipe is one division and then a multiplication for each ingredient. A recipe for 4 cooked for 6 needs 6 ÷ 4 = 1.5 times every amount: 250 g of flour becomes 375 g and 2 eggs become 3.
Going down works the same way with a factor below one. Halving a recipe uses 0.5; cooking for 2 from a recipe for 6 uses one third. Amounts that do not come out round, such as two thirds of an egg, are shown with the exact figure so you can decide how to measure them.
Units do not change when you scale, so grams stay grams and cups stay cups. If you want to switch between cups and grams, that is a conversion rather than a scaling, and it depends on the ingredient.
Formula
factor = servings wanted ÷ recipe servings; new amount = amount × factor
One factor is found from the servings, and every ingredient amount is multiplied by it.
Worked examples
- Try these numbers
A recipe for 4, cooked for 6
- The factor is 6 ÷ 4 = 1.5.
- 250 g of flour × 1.5 = 375 g.
- 2 eggs × 1.5 = 3 eggs; 300 ml of milk × 1.5 = 450 ml.
Multiply everything by 1.5: 375 g flour, 3 eggs, 450 ml milk.
- Try these numbers
A recipe for 6, cooked for 2
- The factor is 2 ÷ 6 = 0.3333.
- 3 eggs × 0.3333 = 1 egg.
Use one third of every amount — 1 egg instead of 3.
- Try these numbers
Same number of servings
- The factor is 4 ÷ 4 = 1.
- Every amount stays the same: 120 g remains 120 g.
No change — a factor of 1.
Inputs and results
- Recipe serves
- How many servings the recipe as written makes.
- You want
- How many servings you want to make.
- Ingredients
- Each ingredient with its amount and unit, as written in the recipe.
- Scale factor
- Servings wanted divided by servings in the recipe.
- Scaled amounts
- Each amount multiplied by the scale factor, in its original unit.
When to use it
- Cooking a family recipe for a larger or smaller group.
- Turning a restaurant-size batch into a home-size one, or the reverse.
- Checking how much of each ingredient to buy before scaling a recipe for an event.
Common mistakes
- Dividing the wrong way round: the factor is servings wanted divided by servings the recipe makes.
- Scaling an amount but not its unit context, such as treating “1 tin” as a fixed quantity when the tin size matters.
- Rounding every ingredient to a whole number before cooking; small quantities like spices can change taste noticeably.
What it does not do
- Cooking times and pan sizes do not scale in proportion; a larger cake in a deeper tin bakes differently.
- Seasoning, raising agents and thickeners do not always scale linearly; taste and adjust.
- It does not convert between volume and weight, such as cups of flour to grams.
Method and assumptions
The scale factor is the target servings divided by the original servings. Each amount is multiplied by that factor without rounding.
Displayed amounts are shown to at most two decimal places; when that rounds an amount, the exact figure remains in the working.
Assumptions
- Every ingredient scales in direct proportion to servings.
- Units are kept as entered.
Edge cases
- Servings of zero are refused, because a recipe cannot be scaled from or to nothing.
- An ingredient with no amount, such as “salt to taste”, can be left blank and is listed unchanged.
- Fractional servings such as 2.5 are allowed.
Sources and corrections
This calculator uses an elementary formula, so it needs no outside data source. The method, the rounding rules and how a reported error is corrected are set out in the site standards.
Result looks wrong?
Send the inputs you used and the answer you expected. Every report is checked against the formula and its tests, and confirmed errors are corrected in public.