Power Converter Online

Converting between watts, horsepower, and BTU per hour comes up in electrical specs, engine comparisons, and HVAC equipment ratings. This tool converts any power value across metric, imperial, and thermal units instantly.

How it works

Enter a value, select the unit you're converting from, and the tool calculates the equivalent in every other supported unit using standard conversion constants. Everything runs client-side in your browser.

How to use it

1. Select Power from the unit categories if it isn't pre-selected
2. Enter your numeric value
3. Pick your source unit from the dropdown
4. Read the converted values across all units in the results panel
5. Click any result to copy it

Supported units

Watts (W), kilowatts (kW), megawatts (MW), milliwatts (mW), horsepower (hp), BTU per hour (BTU/hr), calories per second, and foot-pounds per minute.

A few things worth knowing

• Watts: The SI unit of power — one joule of energy per second. Used for electrical ratings (appliances, light bulbs, solar panels)
• Horsepower: An imperial unit historically defined by steam engine comparisons to horses. One mechanical horsepower ≈ 745.7 watts. Commonly used for car engines and power tools
• BTU/hr: Used in HVAC. One BTU is the energy needed to raise one pound of water by 1°F. Air conditioner and heater capacity is typically stated in BTU/hr or its equivalent in tons (1 ton = 12,000 BTU/hr)
• kW to hp: Multiply kW by 1.341. Multiply hp by 0.7457 to go the other way

FAQ

How do I convert kilowatts to horsepower? Multiply kilowatts by 1.341. For example, a 100 kW electric motor produces about 134 hp.

What does BTU/hr measure? The rate of heat transfer. An air conditioner rated at 10,000 BTU/hr removes that much heat from a room per hour.

Are the conversions exact? The tool uses standard accepted conversion constants (e.g. 1 hp = 745.69987 W exactly by definition). Results are accurate to the limits of floating-point arithmetic.

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