Convert Therms to Calories
1 therm (thm) equals 25210420.65 calories (cal).
1 thm = 25210420.65 cal
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk therm to calorie converter to paste a column from Excel.
How to Convert Therm to Calorie
- 1 thm = 25210420.65 cal
- 1 cal = 3.966613703 × 10⁻⁸ thm
- Example: convert 15 thm to cal: 15 thm = 15 × 25210420.65 cal = 378156309.8 cal
Reference conditions. thm: US therm, 100 000 BTU (59 °F), 105.4804 MJ as given by NIST SP 811. The EC therm is 105.506 MJ. cal: Thermochemical calorie, 4.184 J exactly. The International Table calorie is 4.1868 J.
Formula
cal = thm × 25210420.6501
Derivation from SI units:
- 1 thm (US) = 1.054804 × 10⁸ J (NIST SP 811)
- 1 cal (thermochemical) = 4.184 J (exact)
- 1 thm = 105480400 J ÷ 4.184 J per cal = 25210420.6501 cal
Both units are defined exactly, so the factor is exact. Therm definition: therm; Calorie definition: calorie.
Worked examples
- A reading of 20 thm converts to 504208413 cal.
20 thm × 25210420.65 = 504208413 cal - A value of 100 thm is 2521042065 cal.
100 thm × 25210420.65 = 2521042065 cal
Therm to Calorie conversion table
| Therms (thm) | Calories (cal) |
|---|---|
| 1 thm | 25210420.65 cal |
| 5 thm | 126052103.3 cal |
| 10 thm | 252104206.5 cal |
| 20 thm | 504208413 cal |
| 50 thm | 1260521033 cal |
| 75 thm | 1890781549 cal |
| 100 thm | 2521042065 cal |
| 500 thm | 12605210330 cal |
| 1000 thm | 25210420650 cal |
Where it's used
Therms are used for US and UK natural-gas bills, while calories appear in chemistry and calorimetry. Both measure energy, work and heat, so the conversion is a fixed factor.
Therm to other energy units
| Conversion | 1 thm equals |
|---|---|
| therm to joule | 105480400 J |
| therm to kilojoule | 105480.4 kJ |
| therm to megajoule | 105.4804 MJ |
| therm to calorie | 25210420.65 cal |
| therm to kilocalorie | 25210.42065 kcal |
| therm to watt-hour | 29300.11111 Wh |
| therm to kilowatt-hour | 29.30011111 kWh |
| therm to BTU | 99976.12898 BTU |
| therm to electronvolt | 6.583568738 × 10²⁶ eV |
| therm to foot-pound | 77798350.53 ft·lbf |
| therm to erg | 1.054804 × 10¹⁵ erg |
Frequently asked questions
How many calories are in 1 therm?
1 thm = 25210420.65 cal.
How do I convert therms to calories?
Multiply the value in thm by 25210420.65. For example, 15 thm × 25210420.65 = 378156309.8 cal.
Is the thm to cal conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "therm (U.S.)".
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "calorie (thermochemical) (cal_th)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Therms to Calories. Retrieved October 17, 2026, from https://scientificconverters.com/energy/therms-to-calories/
IEEE
Scientific Converters, "Convert Therms to Calories," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/therms-to-calories/