dopecalc

Power Converter

Convert between watts, kilowatts, megawatts, mechanical horsepower, metric horsepower, BTU per hour, and foot-pounds per second.

About this Calculator

Convert between watts, kilowatts, megawatts, mechanical horsepower, metric horsepower, BTU per hour, and foot-pounds per second.

Formula & Calculations

Formula

Result = Input value × (Conversion factor from unit / Conversion factor to unit), normalized to watts
Where:
  • W=Watts (SI base unit, 1 W = 1 J/s)
  • kW=Kilowatts (1 kW = 1000 W)
  • MW=Megawatts (1 MW = 1,000,000 W)
  • hp(I)=Mechanical horsepower (1 hp = 745.7 W)
  • hp(M)=Metric horsepower (1 hp(M) = 735.499 W)
  • BTU/h=BTU per hour (1 BTU/h ≈ 0.293071 W)
  • ft·lb/s=Foot-pounds per second (1 ft·lb/s = 1.35582 W)

Assumptions

  • Mechanical horsepower uses the standard 745.69987 W definition.
  • Metric horsepower uses the DIN definition of 735.49875 W.
  • All conversions are normalized through watts.

Calculation Examples

Example 1

Inputs:100 hp to kW
Result:74.57 kW

100 × 745.7 ÷ 1000 = 74.57 kW.

Example 2

Inputs:1 kW to BTU/h
Result:3412.14 BTU/h

1 × 1000 ÷ 0.293071 = 3412.14 BTU/h.

Example 3

Inputs:250 metric hp to watts
Result:183,874.7 W

250 × 735.499 = 183,874.7 W.

Frequently Asked Questions

What is the difference between mechanical and metric horsepower?

Mechanical horsepower (also called imperial) equals 745.7 watts and is used in the US and UK. Metric horsepower equals 735.5 watts and is used in continental Europe. A car rated at 100 hp(M) is slightly less powerful than one rated at 100 hp(I).

Why does my car use kW instead of hp?

Many countries require engine power ratings in kilowatts (kW) by law. 1 kW ≈ 1.341 mechanical hp. Electric vehicle motors are typically rated in kW.