Convert Therms to Watt-hours
1 therm (thm) equals 29300.11111 watt-hours (Wh).
1 thm = 29300.11111 Wh
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk therm to watt-hour converter to paste a column from Excel.
How to Convert Therm to Watt-hour
- 1 thm = 29300.11111 Wh
- 1 Wh = 0.00003412956341 thm
- Example: convert 15 thm to Wh: 15 thm = 15 × 29300.11111 Wh = 439501.6667 Wh
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.
Formula
Wh = thm × 29300.11111111
Derivation from SI units:
- 1 thm (US) = 1.054804 × 10⁸ J (NIST SP 811)
- 1 Wh = 1 W × 3600 s = 3600 J
- 1 thm = 105480400 J ÷ 3600 J per Wh = 29300.11111111 Wh
Both units are defined exactly, so the factor is exact. Therm definition: therm; Watt-hour definition: watt-hour.
Worked examples
- A reading of 20 thm converts to 586002.2222 Wh.
20 thm × 29300.11111 = 586002.2222 Wh - A value of 100 thm is 2930011.111 Wh.
100 thm × 29300.11111 = 2930011.111 Wh
Therm to Watt-hour conversion table
| Therms (thm) | Watt-hours (Wh) |
|---|---|
| 1 thm | 29300.11111 Wh |
| 5 thm | 146500.5556 Wh |
| 10 thm | 293001.1111 Wh |
| 20 thm | 586002.2222 Wh |
| 50 thm | 1465005.556 Wh |
| 75 thm | 2197508.333 Wh |
| 100 thm | 2930011.111 Wh |
| 500 thm | 14650055.56 Wh |
| 1000 thm | 29300111.11 Wh |
Where it's used
Therms are used for US and UK natural-gas bills, while watt-hours appear in battery capacity (phone ≈ 15 Wh; airline limit 100 Wh per power bank). 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 watt-hours are in 1 therm?
1 thm = 29300.11111 Wh.
How do I convert therms to watt-hours?
Multiply the value in thm by 29300.11111. For example, 15 thm × 29300.11111 = 439501.6667 Wh.
Is the thm to Wh 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, "watt hour (W·h)".
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 Watt-hours. Retrieved October 17, 2026, from https://scientificconverters.com/energy/therms-to-watt-hours/
IEEE
Scientific Converters, "Convert Therms to Watt-hours," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/therms-to-watt-hours/