How to Convert Watt-hours to Therms (Wh to thm)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert watt-hours into therms by hand, with examples and a quick-reference table.
The conversion
To convert watt-hours to therms, multiply the value by 3.412142e-05. To go the other way, divide by the same number (or multiply by 29,307.1070158333). Because the factor is tiny, scientific notation keeps the numbers manageable.
Therms = watt-hours × 3.412142e-05
Worked examples
- 3 Wh = 0.000102 thm
- 12.5 Wh = 0.000427 thm
- 75 Wh = 0.002559 thm
Watt-hours to Therms table
| Watt-hours | Therms |
|---|---|
| 1 Wh | 3.412142e-5 thm |
| 2 Wh | 6.824283e-5 thm |
| 5 Wh | 0.000171 thm |
| 10 Wh | 0.000341 thm |
| 20 Wh | 0.000682 thm |
| 25 Wh | 0.000853 thm |
| 50 Wh | 0.001706 thm |
| 100 Wh | 0.003412 thm |
| 250 Wh | 0.00853 thm |
| 500 Wh | 0.017061 thm |
| 1,000 Wh | 0.034121 thm |
Common questions
Is Wh to thm exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Therms to Watt-hours converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
For any value, use the Watt-hours to Therms Converter or browse all energy converters.
Run your own numbers: Watt-hours to Therms Converter