Power Converter

Convert power between watts, kilowatts, horsepower, BTU/h and mechanical units.

Convert power units instantly. Free watts, kilowatts, horsepower, BTU converter for engines, appliances and HVAC.

About Power Units

Convert power between watts, kilowatts, horsepower, BTU/h and mechanical units.

Power is energy per second, so every unit reduces to watts: a mechanical horsepower is defined as 745.7 W, a BTU per hour about 0.293 W. Enter any value to convert across electrical, mechanical, and thermal power units.

Note the horsepower family: this tool uses mechanical (imperial) horsepower; metric PS differs slightly at 735.5 W. Everything runs in your browser.

Where it is used

Comparing engine outputs, sizing HVAC and heaters, checking appliance loads, and engineering homework.

How to use the Power Units

  1. Value — enter the value (e.g. 100).
  2. From — enter the value.
  3. To — enter the value.
  4. Calculate — press the Calculate button to see the result instantly above.

Formula

All units anchored to watts (1 hp = 745.7 W, 1 BTU/h ≈ 0.293 W).

Examples

Example

value:100
from:hp
to:kW
Result: 100 Horsepower = 74.57 Kilowatts

Frequently Asked Questions

Why 745.7 watts per horsepower?
James Watt defined it as 550 foot-pounds per second, which converts to exactly 745.69987 W. Metric horsepower (PS) is a rounder 735.5 W.
Watts vs watt-hours?
Watts are power (rate); watt-hours are energy (power × time). A 100 W bulb running 10 hours uses 1 kWh.
What size heater for a room?
Roughly 100 W per square meter in temperate climates (10 W per square foot). Insulation and ceilings shift this considerably.
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