Recipe Scaler Calculator
Scale any recipe up or down by changing the number of servings. Instantly adjust ingredient amounts while keeping proportions perfect.
Did this tool work for you?
How to use this calculator
Divides the target servings by the original servings to get a scale factor, then multiplies each ingredient amount by that factor.
- 1
Enter the original number of servings the recipe is written for.
- 2
Enter your target number of servings.
- 3
Fill in the amount and unit for each ingredient.
- 4
The scaled amounts appear instantly — repeat for as many ingredients as needed.
Frequently asked questions
How is the scale factor calculated?
Target servings divided by original servings, shown to three decimals. Going from 6 servings to 4 gives ×0.667, from 4 to 10 gives ×2.5 and from 3 to 7 gives ×2.333. Each ingredient amount is then multiplied by the unrounded factor, so the displayed three-decimal factor is for reading only.
Does the calculator convert units as it scales?
No. The unit box is free text that is copied back unchanged, so 1.5 cups scaled by two thirds comes out as "1 cups" and 2 tbsp becomes "1.3333 tbsp". Turning 1.3333 tbsp into 1 tbsp plus 1 tsp, or into millilitres, is up to you or the kitchen measurement converter.
How many ingredients can I scale?
Three. The form has three amount and unit pairs and nothing else, so a recipe with ten ingredients needs to be scaled in several passes, or you can work out the factor once and multiply the remaining lines yourself.
How are the numbers rounded?
Scaled amounts are rounded to four decimal places and trailing zeros are dropped, so 625 g shows as 625 and 2.3333 cup stays at four decimals. Whole items are not rounded, which is why 3 eggs scaled by 2.5 appears as 7.5 eggs and you must decide whether to use 7 or 8.
What happens if I clear a field or enter zero?
An original servings count of 0, which is also what a cleared box becomes, falls back to 4, and a negative one is raised to 0.01. A target of 0, which is also what a cleared box becomes, gives a factor of ×0 and zero for every ingredient. Cleared ingredient amounts count as 0.
Does it adjust cooking time, pan size or seasoning?
No. Only the three amounts are multiplied by the factor. Baking time, tin size, oven temperature, and how much salt, spice or raising agent a larger batch really needs are not modelled, so apply your own judgement to those.
Can I scale by something other than servings?
Yes, as long as the ratio is right. Enter 1 as the original and 2.5 as the target to multiply every line by 2.5, or enter the weight of the original batch and the weight you want.
Scaling recipes by servings: the factor, the rounding and the limits
A single multiplier for every line
The tool divides the number of servings you want by the number the recipe was written for, and multiplies each of three ingredient amounts by that ratio. Nothing else changes: the unit text you type is passed straight through, and no ingredient is treated differently from another. An original of 0 (what a cleared box becomes) is treated as 4 servings, while a target of 0 scales everything to zero, so check both boxes before reading the answer.
Three scaling runs
The table shows results from the calculator for three different jobs, using the units as typed. Notice that the unit labels stay as entered, even when the number becomes 1 or a fraction.
| Servings | Factor | Ingredient 1 | Ingredient 2 | Ingredient 3 |
|---|---|---|---|---|
| 6 to 4 | ×0.667 | 1.5 cups to 1 cups | 2 tbsp to 1.3333 tbsp | 0.25 tsp to 0.1667 tsp |
| 4 to 10 | ×2.5 | 3 eggs to 7.5 eggs | 250 g to 625 g | 1 tsp to 2.5 tsp |
| 3 to 7 | ×2.333 | 1 cup to 2.3333 cup | 1 tbsp to 2.3333 tbsp | 1 tsp to 2.3333 tsp |
Turning decimals into measures you can use
The 3-to-7 run shows why exact answers can be awkward: 2.3333 tbsp is not a spoon marking. Since a tablespoon holds 3 teaspoons, 2.3333 tbsp is 2 tbsp plus 1 tsp, and 1.3333 tbsp from the first run is 1 tbsp plus 1 tsp. Quantities as small as 0.1667 tsp, about a sixth of a teaspoon, are best measured by a pinch or by eye. For whole items such as the 7.5 eggs, beat an extra egg and add roughly half of it by weight or volume.
What stays outside the maths
Only amounts are scaled, which leaves several things for you to judge. A bigger batch usually needs a bigger pan or several pans, and the cooking time rarely moves in step with the factor. Seasoning, spice heat and raising agents may not behave proportionally when a recipe is doubled or halved, so season gradually and taste along the way.
Edge cases worth knowing
Setting the target to 0 produces a ×0 factor and a zero for every ingredient. Only three ingredient slots exist, so the tool suits the core lines of a short recipe or a quick check of a few key items. For longer lists, take the factor from the first row, keep it written down, and multiply the rest yourself with a phone calculator.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →