💡 Power Conversion

Convert between power units for engineering, automotive, energy, and science. Supports watts (W), kilowatts (kW), megawatts (MW), horsepower (hp), BTUs per hour (BTU/h), foot-pounds per minute, and calories per second.

Power conversion calculates the rate of energy transfer or work performed over time. The SI base unit is the Watt (W, 1 Joule/s). 1 kilowatt (kW) equals 1,000 Watts, 1 metric horsepower (PS/cv) equals 735.49875 Watts, and 1 mechanical imperial horsepower (hp) is standardized as approx. 745.69987 Watts (550 ft·lbf/s).

Metrological Standards & Base Equation

1 horsepower = 745.7 watts = 0.7457 kW. 1 kW = 1.341 horsepower. 1 W = 3.412 BTU/h.

Power calculations strictly distinguish between mechanical horsepower (550 ft·lbf/s ≈ 745.69987 W) codified by James Watt, metric horsepower (DIN 66036 = 75 kp·m/s = 735.49875 W), and electrical horsepower (exactly 746 W) per NIST SP 811.

Primary References: NIST SP 811 (2008 Edition) · CODATA Recommended Values · Standards Directory

Supported Power Units (5 Total)

Power Unit Definitions and Scaling Factors
Unit Symbol Unit Name System Equivalent in Watt
W Watt Metric Reference Standard (1 W)
kW Kilowatt Metric 1 kW = 1000 W
MW Megawatt Metric 1 MW = 1000000 W
hp Horsepower Imperial 1 hp = 745.7 W
BTU/h BTU/h Imperial 1 BTU/h = 0.29307107 W

Popular Power Conversions

Horsepower to Kilowatts

hp → kW — engine power & automotive

Kilowatts to Horsepower

kW → hp — international specs

Watts to BTU/h

W → BTU/h — heating & cooling

MW to kW

MW → kW — power plant output

Horsepower to Watts

hp → W — mechanical power

Common Use Cases

  • Automotive engine specs (hp↔kW)
  • Electrical appliances (W↔kW)
  • HVAC systems (BTU/h↔W)
  • Industrial machinery (MW↔kW)
  • Fitness equipment (W↔hp)

Frequently Asked Questions

How many kilowatts in one horsepower?

One horsepower equals 0.7457 kilowatts. To convert hp to kW, multiply by 0.7457.

How do I convert watts to BTU/h?

Multiply watts by 3.412 to get BTU per hour. For example, 1,000 W × 3.412 = 3,412 BTU/h.