How to Convert British thermal units to Watt-hours (BTU to Wh)
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 british thermal units into watt-hours by hand, with examples and a quick-reference table.
The conversion
To convert british thermal units to watt-hours, multiply the value by 0.2930710694. To go the other way, divide by the same number (or multiply by 3.4121416416). For a quick estimate, multiply by about 0.29.
Watt-hours = british thermal units × 0.2930710694
Worked examples
- 3 BTU = 0.879213 Wh
- 12.5 BTU = 3.6634 Wh
- 75 BTU = 21.9803 Wh
British thermal units to Watt-hours table
| British thermal units | Watt-hours |
|---|---|
| 1 BTU | 0.293071 Wh |
| 2 BTU | 0.586142 Wh |
| 5 BTU | 1.4654 Wh |
| 10 BTU | 2.9307 Wh |
| 20 BTU | 5.8614 Wh |
| 25 BTU | 7.3268 Wh |
| 50 BTU | 14.6536 Wh |
| 100 BTU | 29.3071 Wh |
| 250 BTU | 73.2678 Wh |
| 500 BTU | 146.5355 Wh |
| 1,000 BTU | 293.0711 Wh |
Common questions
Is BTU to Wh 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 Watt-hours to British thermal units 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.
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.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Background
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.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For any value, use the British thermal units to Watt-hours Converter or browse all energy converters.
Run your own numbers: British thermal units to Watt-hours Converter