Power and Energy
caltoBTU
Convert thermochemical calories (cal) to International Table BTUs (BTU).
Factor1 cal = 0.003965667 BTU
Converter
cal
Accepts numbers or expressions, e.g. 150 + 14.7
Result
BTU
Rendered to 6 significant figures.
Formula
Formula
BTU = cal × 0.003965667
Multiply any value in thermochemical calories by 0.003965667 to obtain the value in International Table BTUs.
Worked example
Convert 1000 cal to BTU.
- 01Start with 1000 cal.
- 02Multiply by the conversion factor: 1000 × 0.003965667 = 3.96567 BTU.
Result1000 cal = 3.96567 BTU
Conversion table
| cal | BTU |
|---|---|
| 1 | 0.0039657 |
| 2 | 0.0079313 |
| 5 | 0.019828 |
| 10 | 0.039657 |
| 20 | 0.079313 |
| 50 | 0.19828 |
| 100 | 0.39657 |
| 200 | 0.79313 |
| 500 | 1.9828 |
| 1000 | 3.9657 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from cal to BTU?
1 cal equals 0.003965667 BTU. To convert, multiply the value in thermochemical calories by 0.003965667.
How do I convert 1 cal to BTU?
1 cal = 0.00396567 BTU. For any value, multiply by 0.003965667.
How do I convert BTU back to cal?
Divide by the same factor — or equivalently, multiply by 252.1644. So 1 BTU = 252.164 cal.
When would I need to convert thermochemical calorie to International Table BTU?
Energy conversions are needed when reconciling fuel/electrical billing, calculating thermal duties, and aligning calorimetry or HHV/LHV figures across data sources.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).