Watt (W)
SI derived unit: one joule per second.
What is a watt?
- Symbol
- W
- Quantity
- Power
- Unit system
- SI
- Definition
- SI derived unit: one joule per second.
- Exact
- Yes, the value is exact by definition
- Source
- SI Brochure, 9th edition (BIPM, 2019)
Common applications
The SI unit of power. Used for light bulbs, appliances, chargers and audio equipment.
Watt in other power units
- 1 W = 1000 mWMilliwatt
- 1 W = 0.001 kWKilowatt
- 1 W = 0.000001 MWMegawatt
- 1 W = 1e-9 GWGigawatt
- 1 W ≈ 0.00134102209 hpWatt to Horsepower (mechanical) converter
- 1 W ≈ 0.001359621617 PSHorsepower (metric)
- 1 W ≈ 3.412141633 BTU/hWatt to BTU (IT) per hour converter
- 1 W ≈ 0.7375621493 ft·lbf/sFoot-pound-force per second
Watt quick reference
| Watt | Horsepower (mechanical) | BTU (IT) per hour | Kilowatt |
|---|---|---|---|
| 1 W | ≈ 0.00134102209 hp | ≈ 3.412141633 BTU/h | = 0.001 kW |
| 10 W | ≈ 0.0134102209 hp | ≈ 34.12141633 BTU/h | = 0.01 kW |
| 100 W | ≈ 0.134102209 hp | ≈ 341.2141633 BTU/h | = 0.1 kW |
| 1000 W | ≈ 1.34102209 hp | ≈ 3412.141633 BTU/h | = 1 kW |
Where the watt fits
The next smaller power unit is the BTU per hour (BTU/h). 1 W ≈ 3.412141633 BTU/h, and 1 BTU/h ≈ 0.2930710702 W.
The next larger power unit is the foot-pound-force per second (ft·lbf/s). 1 W ≈ 0.7375621493 ft·lbf/s, and 1 ft·lbf/s = 1.3558179483314004 W.
Frequently asked questions
- How many horsepower are in one watt?
- One watt ≈ 0.00134102209 hp (horsepower).
- How many BTUs per hour are in one watt?
- One watt ≈ 3.412141633 BTU/h (BTUs per hour).
- How many kilowatts are in one watt?
- One watt = 0.001 kW (kilowatts).