Convert British thermal units to Calories
1 British thermal unit is 252.164401 cal. One British thermal unit is exactly 252.164400722 calories.
One British thermal unit is 252.1644 calories. To convert British thermal units to calories, multiply by 252.1644; to go the other way, divide by 252.1644 or multiply by 0.0039656668. The factor is exact rather than rounded: it follows from NIST Special Publication 811. The international-table BTU, fixed at exactly 1055.05585262 joules.
Factor checked against the defining standard · How we check
- British thermal units × 252.1644
value * 252.164400722252.164 cal
1 British thermal unit in every energy unit
| Unit | Value | Exact factor |
|---|---|---|
| joules | 1,055.055853 J | × 1,055.05585262 |
| kilojoules | 1.055055853 kJ | × 1.05505585262 |
| calories | 252.1644007 cal | × 252.164400722 |
| kilocalories | 0.2521644007 kcal | × 0.252164400722 |
| watt-hours | 0.2930710702 Wh | × 0.293071070172 |
| kilowatt-hours | 0.0002930710702 kWh | × 0.000293071070172 |
| British thermal units (as entered) | 1 BTU | — |
| foot-pounds | 778.1692623 ft·lbf | × 778.169262266 |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert British thermal units to calories?
- 1.Take the measurement in British thermal units.
- 2.Multiply by 252.1644 — that is how many calories fit in one British thermal unit.
- 3.To go back the other way, divide by 252.1644, or multiply by 0.0039656668.
Worked example: 25 British thermal units to calories
- Formula
- BTU × 252.1644 = cal
- Arithmetic
- 25 × 252.1644 = 6,304.110018 cal
- Answer
- 25 BTU = 6,304.110018 cal
The factor is rounded for display; the figure above is computed from the full value.
British thermal units to calories conversion table
| British thermal units | Calories |
|---|---|
| 1 BTU | 252.164401 cal |
| 2 BTU | 504.328801 cal |
| 3 BTU | 756.493202 cal |
| 4 BTU | 1,008.657603 cal |
| 5 BTU | 1,260.822004 cal |
| 6 BTU | 1,512.986404 cal |
| 7 BTU | 1,765.150805 cal |
| 8 BTU | 2,017.315206 cal |
| 9 BTU | 2,269.479606 cal |
| 10 BTU | 2,521.644007 cal |
| 12 BTU | 3,025.972809 cal |
| 15 BTU | 3,782.466011 cal |
| 20 BTU | 5,043.288014 cal |
| 25 BTU | 6,304.110018 cal |
| 50 BTU | 12,608.220036 cal |
| 100 BTU | 25,216.440072 cal |
| 200 BTU | 50,432.880144 cal |
| 300 BTU | 75,649.320217 cal |
| 500 BTU | 126,082.200361 cal |
| 1000 BTU | 252,164.400722 cal |
| 2000 BTU | 504,328.801444 cal |
| 5000 BTU | 1,260,822.00361 cal |
| 10000 BTU | 2,521,644.00722 cal |
What is a British thermal unit?
The international-table BTU, fixed at exactly 1055.05585262 joules. Roughly the heat needed to raise a pound of water by one degree Fahrenheit, which is where it came from.
What is a calorie?
The thermochemical calorie: exactly 4.184 joules by definition. This is the small calorie — the one on a food label is a thousand of these, which is the single most common confusion in this group.
How many calories are in a British thermal unit?
One British thermal unit is 252.1644 calories. Going the other way, one calorie is 0.0039656668 British thermal units. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every energy unit here
| Unit | Symbol | One of these is |
|---|---|---|
| Joules | J | the base unit |
| Kilojoules | kJ | 1000 joule |
| Calories | cal | 4.184 joule |
| Kilocalories | kcal | 4184 joule |
| Watt-hours | Wh | 3600 joule |
| Kilowatt-hours | kWh | 3600000 joule |
| British thermal units | BTU | 1055.0559 joule |
| Foot-pounds | ft·lbf | 1.3558179 joule |
Source: NIST Special Publication 811 — the thermochemical calorie is exactly 4.184 J
Questions people actually ask
- How many calories are in a British thermal unit?
- 252.1644. The thermochemical calorie: exactly 4.184 joules by definition. This is the small calorie — the one on a food label is a thousand of these, which is the single most common confusion in this group.
- How do I convert calories back to British thermal units?
- Divide by 252.1644, or multiply by 0.0039656668 — they are the same operation.
Other energy conversions
Calories to British thermal units — the same conversion the other way.