Calorie to BTU (cal to BTU)
Result
0.003965666831 BTU
Formula
BTU = cal × 0.003965666831
1 cal = 0.003965666831 BTU, and 1 BTU = 252.1644007 cal.
The joule is the SI unit of energy. The calorie used here is the thermochemical calorie, exactly 4.184 J; a kilowatt-hour is exactly 3.6 MJ; the BTU is the International Table BTU (1,055.05585262 J).
Worked examples
- 1 cal × 0.003965666831 = 0.0039656668 BTU
- 10 cal × 0.003965666831 = 0.039656668 BTU
- 100 cal × 0.003965666831 = 0.39656668 BTU
Common mistakes
- Food "Calories" (capital C) are kilocalories: a 250 Calorie snack contains 250 kcal, or 1,046 kJ.
- kW is power and kWh is energy: a 2 kW heater running for 3 hours uses 6 kWh.
- The International Table calorie (4.1868 J) is slightly larger than the thermochemical calorie (4.184 J); engineering steam tables use the former.
Calorie to BTU table
| Calorie (cal) | BTU (BTU) |
|---|---|
| 1 | 0.0039656668 |
| 2 | 0.0079313337 |
| 5 | 0.019828334 |
| 10 | 0.039656668 |
| 20 | 0.079313337 |
| 50 | 0.19828334 |
| 100 | 0.39656668 |
| 1,000 | 3.9656668 |
The units
- Calorie (cal)
- 1 Calorie = 4.184 Joule.
- BTU (BTU)
- British thermal unit (International Table): 1,055.05585262 J — roughly the heat to warm one pound of water by 1 °F.
Sources for these factors
- Guide for the Use of the International System of Units (SP 811), Appendix B: conversion factors — NIST
- The International System of Units (SI Brochure), 9th edition — BIPM
Last reviewed against these sources. An automated check recomputes every factor from its definition on each build. How we check accuracy