---
title: "Fat-free mass index"
method: GET
path: "/calculate/ffmi"
tags: ["Body metrics"]
---

# Fat-free mass index

`GET /calculate/ffmi`

## Request

- Base URL: `https://myplate.food/api/v1`
- URL: `https://myplate.food/api/v1/calculate/ffmi`
- Auth: none declared

Fat-free mass index (FFMI) and its height-normalized value from weight, height, body-fat % and sex (Kouri 1995 normalization).

Cites its source in every response: `source` (the formula + published reference) and `canonical_url` (https://myplate.food/ffmi-calculator), plus a `disclaimer`.

## Query parameters

- `unit` 'metric' | 'imperial'
- `sex` 'male' | 'female', required
- `weight` number, required
- `height` number, required
- `body_fat` number, required

## Response `200`

Calculation result with citation envelope.

- CitedResult: Calculation result. Shape varies by endpoint, but every result carries the citation envelope fields below alongside the calculator's own numbers.
  - `calculator` string, required: The endpoint name.
  - `inputs` object: The parsed, normalized inputs the result was computed from.
  - `source` string, required: The formula and published reference behind the number.
  - `canonical_url` string, uri, required: The matching myplate.food page.
  - `disclaimer` string: Present on health calculators.

## Other responses

- `400`: Invalid or missing parameters.

---

[API](https://skmtc.dev/myplate/apis/myplate-food-nutrition-api.md) · [All operations](https://skmtc.dev/myplate/apis/myplate-food-nutrition-api/llms.txt) · [OpenAPI document](https://skmtc.dev/myplate/apis/myplate-food-nutrition-api/revisions/cb7ba731c59b?raw)