# Recipe Scaler

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

- Calculator id: `recipe-scaler` · Category: Food & Cooking (`food`) · Tool name: `scale_recipe`
- Canonical page: https://tttkmbb.com/food/recipe-scaler · This document: https://tttkmbb.com/food/recipe-scaler.md · JSON definition: https://tttkmbb.com/food/recipe-scaler.json

## Purpose

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

**Use when:** 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).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `original_servings` | number | servings | required | Number of servings (or yield) the original recipe makes. (> 0, max 100000) |
| `desired_servings` | number | servings | required | Number of servings you want to make. (> 0, max 100000) |
| `ingredient_amounts` | number_list |  | optional | Optional list of ingredient quantities from the original recipe, in any units, in order; each is multiplied by the scale factor. |

## Output

| Field | 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. |

## 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.

## Data Sources

- BC Campus – Basic Kitchen and Food Service Management: Converting and Adjusting Recipes and Formulas — https://opentextbc.ca/basickitchenandfoodservicemanagement/chapter/convert-and-adjust-recipes-and-formulas/ (textbook, retrieved 2026-09-23)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/recipe-scaler?original_servings=…&desired_servings=…`
- `POST https://tttkmbb.com/api/v1/calculate/recipe-scaler` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/recipe-scaler · OpenAPI operationId `scale_recipe` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "recipe-scaler", "inputs": {…}}`

## Example

- 4 → 10 servings, amounts 200, 3, 0.5: inputs `{"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: inputs `{"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
```

## Limitations

You need to convert between measurement units (use cooking-converter) or to work with baker's percentages for dough (use bakers-percentage). 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. All values are computed from the formula above; no measurement or live data is involved.

## 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

- [Cooking Measurement Converter](https://tttkmbb.com/food/cooking-converter.md) — Convert the scaled quantities between cups, tablespoons and millilitres.
- [Baker's Percentage Calculator](https://tttkmbb.com/food/bakers-percentage.md) — Scale bread and pizza dough by flour weight instead.