To convert calories to therms, multiply by 3.965666831e-8.
The calculation uses 1 cal = 3.965666831e-8 thm. Results are displayed to at most 10 significant digits. Definitions can be exact while a displayed decimal is rounded. Match the displayed precision to your original measurement.
Uses the thermochemical calorie, 4.184 J.
Uses 100,000 International Table BTU per therm. Other conventions differ slightly.
The formula
cal- Input unit: calories
thm- Output unit: therms
How to use this calculator
- Enter a value in cal.
- Multiply by the stored conversion factor.
- Read the result in thm; divide by the same factor to convert back.
Worked examples
Worked conversion
1 cal × 3.965666831e-8 ≈ 3.965666831e-8 thm.
Reverse conversion
3.965666831e-8 thm ÷ 3.965666831e-8 ≈ 1 cal. Rounding intermediate values can change the last displayed digit.
Frequently asked questions
What factor does this converter use?
It uses 3.965666831e-8 thm per cal. Uses the thermochemical calorie, 4.184 J. Uses 100,000 International Table BTU per therm. Other conventions differ slightly.
Why can another converter show a slightly different answer?
Check the unit convention first (such as US versus Imperial or decimal versus binary), then compare rounding. Measurement uncertainty is separate from the unit conversion.
cal to thm table
| cal | thm (rounded) |
|---|---|
| 0 | 0 |
| 1 | 3.965666831e-8 |
| 2 | 7.931333663e-8 |
| 5 | 1.982833416e-7 |
| 10 | 3.965666831e-7 |
| 100 | 0.000003965666831 |