# Calories (small, thermochemical) to Kilocalories (food calories) (cal to kcal)

> Convert calories (small, thermochemical) to kilocalories (food calories): 1 cal = 0.001 kcal. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `calories-to-kcal` · Quantity: Energy (`energy`, base unit J) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/calories-to-kcal · This document: https://tttkmbb.com/conversion/calories-to-kcal.md · JSON: https://tttkmbb.com/conversion/calories-to-kcal.json (add `?value=` for a result)

## Formula

- `1 cal = 0.001 kcal`
- `kilocalories (food calories) = calories (small, thermochemical) × 0.001`
- Reverse: `calories (small, thermochemical) = kilocalories (food calories) × 1000`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 cal = 0.005 kcal
- 12.5 cal = 0.0125 kcal
- 100 cal = 0.1 kcal

## Conversion table

| Calories (small, thermochemical) (cal) | Kilocalories (food calories) (kcal) |
| --- | --- |
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 6 | 0.006 |
| 7 | 0.007 |
| 8 | 0.008 |
| 9 | 0.009 |
| 10 | 0.01 |
| 15 | 0.015 |
| 20 | 0.02 |
| 25 | 0.025 |
| 30 | 0.03 |
| 40 | 0.04 |
| 50 | 0.05 |
| 75 | 0.075 |
| 100 | 0.1 |
| 200 | 0.2 |
| 250 | 0.25 |
| 500 | 0.5 |
| 1000 | 1 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=cal&to_unit=kcal` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"cal","to_unit":"kcal"}`
- All energy units: https://tttkmbb.com/api/v1/units?quantity=energy · full converter: [Energy Converter](https://tttkmbb.com/conversion/energy.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many kilocalories (food calories) are in one calorie?**

1 cal = 0.001 kcal. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

**What is the formula to convert calories (small, thermochemical) to kilocalories (food calories)?**

Multiply the value in calories (small, thermochemical) by 0.001: kilocalories (food calories) = calories (small, thermochemical) × 0.001. For example, 5 cal = 0.005 kcal.

**How do I convert kilocalories (food calories) back to calories (small, thermochemical)?**

Multiply by the inverse factor 1000 (calories (small, thermochemical) = kilocalories (food calories) × 1000), or use the kilocalories (food calories)-to-calories (small, thermochemical) page.

## Related conversions

- [Kilocalories (food calories) to calories (small, thermochemical)](https://tttkmbb.com/conversion/kcal-to-calories.md) (reverse)
- [Kilocalories (food calories) to Kilojoules](https://tttkmbb.com/conversion/kcal-to-kj.md)
- [Kilojoules to Kilocalories (food calories)](https://tttkmbb.com/conversion/kj-to-kcal.md)
- [Joules to Calories (small, thermochemical)](https://tttkmbb.com/conversion/joules-to-calories.md)
- [Calories (small, thermochemical) to Joules](https://tttkmbb.com/conversion/calories-to-joules.md)
- [Kilowatt-hours to Megajoules](https://tttkmbb.com/conversion/kwh-to-mj.md)
- [Megajoules to Kilowatt-hours](https://tttkmbb.com/conversion/mj-to-kwh.md)
- [Kilowatt-hours to BTU](https://tttkmbb.com/conversion/kwh-to-btu.md)
- [BTU to Kilowatt-hours](https://tttkmbb.com/conversion/btu-to-kwh.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)