Watt (W)
The watt (W) is the SI unit of power: one joule per second.
Symbol: W
Quantity: power (energy per unit time)
SI relation: W is the coherent SI unit of power.
Derivation: 1 W = 1 J/s = 1 kg·m²·s⁻³
Exact: yes, by definition
History
Named after James Watt, whose steam-engine improvements also led to the horsepower unit.
Typical uses
- Electrical appliance ratings
- Heating and cooling loads
- Motor and pump power
Convert watts to other units
| Conversion | 1 W equals | Reverse |
|---|---|---|
| watt to kilowatt | 0.001 kW | kilowatt to watt |
| watt to horsepower | 0.00134102209 hp | horsepower to watt |
| watt to BTU per hour | 3.412141633 BTU/h | BTU per hour to watt |
| watt to refrigeration ton | 0.0002843451361 TR | refrigeration ton to watt |
| watt to megawatt | 0.000001 MW | megawatt to watt |
| watt to metric horsepower | 0.001359621617 PS | metric horsepower to watt |
| watt to milliwatt | 1000 mW | milliwatt to watt |
| watt to kilocalorie per hour | 0.8598452279 kcal/h | kilocalorie per hour to watt |
| watt to foot-pound per second | 0.7375621493 ft·lbf/s | foot-pound per second to watt |
Open the Power Converter to convert any value between all units.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4, coherent derived units with special names.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Watt (W). Retrieved October 17, 2026, from https://scientificconverters.com/units/watt/
IEEE
Scientific Converters, "Watt (W)," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/units/watt/