The watt (symbol: W) is a unit of power or radiant flux. In the International System of Units (SI), it is defined as a derived unit of (in SI base units)[1][2] 1 kg⋅m2⋅s−3 or, equivalently,[3] 1 joule per second. It is used to quantify the rate of energy transfer. The watt is named after James Watt (1736-1819), an 18th-century Scottish inventor.

Unit systemSI derived unit
Unit ofPower
Named afterJames Watt
1 W in ...... is equal to ...
   SI base units   kgm2s−3
   CGS units   107 ergs−1
   English Engineering Units   0.7375621 ft⋅lbf/s = 0.001341022 hp