# Calories Burned Calculator

> Estimates the calories burned during an activity from body weight, duration and the activity's MET value from the 2011 Compendium of Physical Activities, using the ACSM metabolic equation kcal/min = MET × 3.5 × kg / 200.

- Calculator id: `calories-burned` · Category: Sports & Fitness (`fitness`) · Tool name: `estimate_calories_burned`
- Canonical page: https://tttkmbb.com/fitness/calories-burned · This document: https://tttkmbb.com/fitness/calories-burned.md · JSON definition: https://tttkmbb.com/fitness/calories-burned.json

## Purpose

Estimates the calories burned during an activity from body weight, duration and the activity's MET value from the 2011 Compendium of Physical Activities, using the ACSM metabolic equation kcal/min = MET × 3.5 × kg / 200.

**Use when:** You need an estimate of energy expenditure for a workout, sport or chore of known duration for a person of known weight.

**Do not use when:** You need total daily calorie needs (use tdee) or resting expenditure (use bmr); MET values are population averages and ignore fitness level, terrain and intensity within a category.

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `weight_kg` | number | kg | required | Body weight in kilograms. (> 0, max 700) |
| `duration_minutes` | number | min | required | Duration of the activity in minutes. (> 0, max 1440) |
| `activity` | enum: walking_3_5_mph \| running_6_mph \| running_8_mph \| cycling_moderate \| swimming_laps_moderate \| weight_training \| yoga \| hiking \| jump_rope \| rowing_moderate \| elliptical \| basketball \| soccer \| tennis \| dancing \| housework |  | required | Activity and intensity; each maps to a MET value from the 2011 Compendium of Physical Activities. |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `calories_kcal` | number | kcal | Gross energy expenditure for the session (includes resting metabolism during that time). |
| `kcal_per_minute` | number | kcal/min | Energy expenditure per minute. |
| `kcal_per_hour` | number | kcal/h | Energy expenditure per hour of the activity. |
| `met` | number | MET | Metabolic equivalent of the activity (1 MET = 3.5 ml O2/kg/min, resting). |
| `activity_label` | string |  | Activity description used, with its MET value. |

## Formula

`kcal_per_minute = MET × 3.5 × weight_kg / 200; calories_kcal = kcal_per_minute × duration_minutes`

3.5 ml O2/kg/min is the resting oxygen uptake of 1 MET and 1 litre of O2 corresponds to about 5 kcal, giving kcal/min = MET × 3.5 × kg / 200. Net calories above rest are roughly (MET − 1) / MET of the gross value.

## Data Sources

- Ainsworth BE et al. (2011) 2011 Compendium of Physical Activities: a second update of codes and MET values, Med Sci Sports Exerc 43:1575-1581 — https://pubmed.ncbi.nlm.nih.gov/21681120/ (peer_reviewed, retrieved 2026-09-23)
- Compendium of Physical Activities – online MET tables (2011 and 2024 editions) — https://pacompendium.com/ (reference, 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/calories-burned?weight_kg=…&duration_minutes=…&activity=…`
- `POST https://tttkmbb.com/api/v1/calculate/calories-burned` 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/calories-burned · OpenAPI operationId `estimate_calories_burned` 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": "calories-burned", "inputs": {…}}`

## Example

- 70 kg, running 6 mph, 30 min: inputs `{"weight_kg":70,"duration_minutes":30,"activity":"running_6_mph"}` → `{"calories_kcal":360,"kcal_per_minute":12.01,"kcal_per_hour":720,"met":9.8}`
- 65 kg, walking 3.5 mph, 60 min: inputs `{"weight_kg":65,"duration_minutes":60,"activity":"walking_3_5_mph"}` → `{"calories_kcal":293,"kcal_per_minute":4.89,"met":4.3}`

```
GET https://tttkmbb.com/api/v1/calculate/calories-burned?weight_kg=70&duration_minutes=30&activity=running_6_mph
```

## Limitations

You need total daily calorie needs (use tdee) or resting expenditure (use bmr); MET values are population averages and ignore fitness level, terrain and intensity within a category. 3.5 ml O2/kg/min is the resting oxygen uptake of 1 MET and 1 litre of O2 corresponds to about 5 kcal, giving kcal/min = MET × 3.5 × kg / 200. Net calories above rest are roughly (MET − 1) / MET of the gross value. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Are these gross or net calories?**

Gross: they include the calories you would have burned resting during the same time (about 1 MET). Subtract weight_kg × duration_minutes / 60 for the net exercise cost.

**Why does the same run burn a different number on my watch?**

Devices add heart rate, speed and personal data; MET tables are averages for a standard 70 kg adult, so ±20 % differences are normal.

## Related

- [TDEE Calculator](https://tttkmbb.com/health/tdee.md) — Daily calorie needs including all activity.
- [BMR Calculator](https://tttkmbb.com/health/bmr.md) — Resting energy expenditure that the gross figure includes.
- [Steps to Distance Calculator](https://tttkmbb.com/fitness/steps-to-distance.md) — Turn a step count into a walking distance first.