Watt Hours to British Thermal Units
Convert watt hours to British thermal units instantly — one watt-hour is 3.41214 British thermal units.
| Watt Hours | British Thermal Units |
|---|---|
| 1 Wh | 3.412142 BTU |
| 2 Wh | 6.824283 BTU |
| 3 Wh | 10.236425 BTU |
| 5 Wh | 17.060708 BTU |
| 10 Wh | 34.121416 BTU |
| 25 Wh | 85.303541 BTU |
| 50 Wh | 170.607082 BTU |
| 100 Wh | 341.214163 BTU |
How to use
- Enter a value in the Watt Hours field.
- The British Thermal Units figure appears immediately — no button to press.
- Typing in the British Thermal Units field converts back to Watt Hours the same way.
- Use the reference table for the values that come up most often.
Watt Hours to British Thermal Units formula
The factor from watt hours to British thermal units is 3.41214163.
BTU = Wh × 3.41214163
Why this factor: the watt-hour and the British thermal unit are both defined against the joule, so dividing one definition by the other gives 3.41214163 directly. Both definitions are set out in full below.
To go the other way, divide by 3.41214163 — or use the British Thermal Units to Watt Hours converter, which is the same calculation reversed.
Worked example
Start with 100 Wh. Multiply by 3.41214163 to get 341.214163 BTU.
100 Wh × 3.41214163 = 341.214163 BTU
The converter above does this for any value you type, in either direction.
What is a watt-hour?
A watt-hour is the energy delivered by one watt of power sustained for one hour.
Definition: Exactly 3,600 joules.
Where it is used: Battery capacity for laptops, e-bikes and power tools, and small-scale energy metering.
Worth knowing: Airline lithium-battery limits are set in watt-hours, which is why laptop and power-bank capacities are labelled in Wh.
What is a British thermal unit?
A BTU is the energy needed to raise one pound of water by one degree Fahrenheit.
Definition: The international-table BTU is about 1,055.056 joules.
Where it is used: US heating and air-conditioning capacity ratings, natural gas pricing, and boiler output.
Worth knowing: Air-conditioner ratings quoted as 'BTU' are really BTU per hour — a rate of cooling, not a quantity of energy.
Watt Hours vs British Thermal Units
The watt-hour is a specialized unit while the British thermal unit is a US customary unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many British thermal units are in a watt-hour?
One watt-hour equals 3.41214163 British thermal units.
What is the formula to convert watt hours to British thermal units?
Multiply the number of watt hours by 3.41214163. To reverse it, divide by 3.41214163 instead.
How do I convert British thermal units back to watt hours?
Divide by 3.41214163, which is the same as multiplying by 0.29307107.
How many British thermal units are in 10 watt hours?
10 Wh works out to 34.121416 BTU.
Is there anything to watch out for with watt hours?
Airline lithium-battery limits are set in watt-hours, which is why laptop and power-bank capacities are labelled in Wh.
How is the watt-hour defined?
Exactly 3,600 joules.