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Recipe Scaler

Computes the conversion factor between an original and a desired number of servings and multiplies a list of ingredient amounts by it.

When to use

You need to enlarge or reduce a recipe for a different number of servings and want every ingredient quantity scaled consistently.

Do not use when: You need to convert between measurement units (use cooking-converter) or to work with baker's percentages for dough (use bakers-percentage).

Formula

scale_factor = desired_servings / original_servings; scaled_amount_i = ingredient_amount_i × scale_factor

Linear scaling is exact for ingredient quantities but not for cooking time, pan size, seasoning or leavening; recipes scaled by more than about 4× usually need adjustment.

Inputs

Parameter	Type	Unit	Required	Description
`original_servings`	number	servings	yes	Number of servings (or yield) the original recipe makes. Range: > 0, ≤ 100000
`desired_servings`	number	servings	yes	Number of servings you want to make. Range: > 0, ≤ 100000
`ingredient_amounts`	number_list		no	Optional list of ingredient quantities from the original recipe, in any units, in order; each is multiplied by the scale factor.

Outputs

Output	Type	Unit	Description
`scale_factor`	number		desired_servings / original_servings; multiply every ingredient by this.
`scale_percent`	number	%	Scale factor as a percentage of the original recipe.
`scaled_amounts`	number_list		Each ingredient amount multiplied by the scale factor (same order and units as the input); only when ingredient_amounts is given.

Example

4 → 10 servings, amounts 200, 3, 0.5: {"original_servings":4,"desired_servings":10,"ingredient_amounts":[200,3,0.5]} → {"scale_factor":2.5,"scale_percent":250,"scaled_amounts":[500,7.5,1.25]}

6 → 2 servings: {"original_servings":6,"desired_servings":2,"ingredient_amounts":[300,2]} → {"scale_factor":0.3333,"scaled_amounts":[100,0.667]}

GET https://tttkmbb.com/api/v1/calculate/recipe-scaler?original_servings=4&desired_servings=10&ingredient_amounts=200%2C3%2C0.5

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/recipe-scaler (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/recipe-scaler · Markdown: https://tttkmbb.com/food/recipe-scaler.md · JSON definition: https://tttkmbb.com/food/recipe-scaler.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="recipe-scaler"
OpenAPI operationId: scale_recipe
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

BC Campus – Basic Kitchen and Food Service Management: Converting and Adjusting Recipes and Formulas (textbook)

FAQ

Do cooking times scale too?

No. A doubled roast or cake needs more time but far less than double; check doneness by temperature or a skewer test rather than scaling the time.

What about salt, spices and yeast?

Scale them linearly as a starting point, then taste: seasoning is often reduced by 10–25 % in large batches, and yeast can be reduced slightly in big doughs because fermentation heat builds up.

Related calculators

Cooking Measurement Converter — Convert the scaled quantities between cups, tablespoons and millilitres.
Baker's Percentage Calculator — Scale bread and pizza dough by flour weight instead.