Watts to BTU Converter
Updated Formulas shown
Multiply watts by 3.41214 to get BTU per hour: a 1,500 W space heater puts out 5,118 BTU/h.
Formula: BTU per hour = watts × 3.4121416331 (exact ratio, shown rounded)
Common values: watts → BTU per hour
| watts | BTU per hour |
|---|---|
| 3.41214 BTU/h | |
| 6.82428 BTU/h | |
| 10.2364 BTU/h | |
| 17.0607 BTU/h | |
| 34.1214 BTU/h | |
| 68.2428 BTU/h | |
| 85.3035 BTU/h | |
| 170.607 BTU/h | |
| 341.214 BTU/h | |
| 853.035 BTU/h | |
| 1,706.07 BTU/h | |
| 3,412.14 BTU/h |
1,500 W in every power unit
- 1.5 kW
- 0.0015 MW
- 2.01153 hp
- 2.03943 PS
- 5,118.21 BTU/h
- 0.426518 ton (AC)
- 1,290.63 kcal/h
How to convert watts to BTU per hour
- Type the value in watts into the converter (or into the right-hand box to go the other way).
- Multiply by 3.4121416331 to get BTU per hour.
- Round to a sensible precision with the Decimals control; the table below covers the values people look up most.
Watt to BTU per hour formula
BTU per hour = watts × 3.4121416331 — 1 W = 3.41214163 BTU/h. Both units are defined exactly (NIST SP 811); the factor above is rounded to 10 decimals, and the converter uses the full-precision ratio.
W to BTU/h conversion table
| watts | BTU/h | kW |
|---|---|---|
| 100 | 341 | 0.1 |
| 250 | 853 | 0.25 |
| 500 | 1,706 | 0.5 |
| 750 | 2,559 | 0.75 |
| 1,000 | 3,412 | 1 |
| 1,200 | 4,095 | 1.2 |
| 1,500 | 5,118 | 1.5 |
| 2,000 | 6,824 | 2 |
| 2,500 | 8,530 | 2.5 |
| 3,000 | 10,236 | 3 |
| 4,000 | 13,649 | 4 |
| 5,000 | 17,061 | 5 |
| 7,500 | 25,591 | 7.5 |
| 10,000 | 34,121 | 10 |
| 15,000 | 51,182 | 15 |
| 20,000 | 68,243 | 20 |
Heat loads from equipment
| equipment | watts | BTU/h |
|---|---|---|
| Space heater (high) | 1,500 | 5,118 |
| Gaming PC under load | 500 | 1,706 |
| Server rack (small) | 2,000 | 6,824 |
| Grow light (LED) | 600 | 2,047 |
| Garage heater (240 V) | 5,000 | 17,061 |
Sizing a garage or workshop heater
A rough rule for an insulated garage is 10 W per ft² (34 BTU/h per ft²) in a moderate climate, so a 2-car 480 ft² garage wants about 4.8 kW (16,400 BTU/h). Uninsulated spaces need much more. A 5,000 W heater on 240 V draws about 21 A — size the circuit and wire with the wire size calculator.
Related converters & calculators
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- BTU CalculatorAC and heater size for any room.
- Wire Size CalculatorMinimum AWG for amps, distance and voltage drop.
- Electricity Cost CalculatorCalculate the cost to run any appliance per day, month and year from its wattage, hours of use and your electricity rate.
- HP to kW Converter1 hp = 0.7457 kW.
- kW to HP Converter1 kW = 1.34102 hp.
- Unit ConverterEvery unit in one fast converter.
Frequently asked questions
How many BTU is 1,500 watts?
5,118 BTU/h.
How many BTU per watt?
1 W = 3.41214 BTU/h.
How many watts to heat a room?
About 10 W per ft² of floor in an insulated room — 1,500 W for a 150 ft² bedroom — more in cold climates or drafty rooms.
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Estimates only. Check quantities with your supplier or contractor before ordering.