Power Converter Free Online
Convert between power units instantly. Supports watt, kilowatt, megawatt, mechanical horsepower, metric horsepower, electrical horsepower, BTU per hour, and foot-pound per second. Useful for engineering, automotive, HVAC, and electrical work.
All Conversions
Pro — bulk batch conversion, API access, history & favorites
API access · Priority queue · Team workspace
How It Works
Enter a Value
Type the number you want to convert into the From input. The conversion runs as you type — no Convert button needed. Decimals and very small or very large numbers are supported via scientific notation.
Pick Source & Target Units
Use the two dropdowns to choose source (From) and destination (To) units. The result updates automatically. Use the swap button to flip the conversion direction in one click.
See All Conversions
Below the main result, the All Conversions panel shows your input value converted into every supported unit at once — perfect for comparing metric vs imperial side by side.
Power Converter Features
SI Watt
Watt is the SI power unit (1 W = 1 J/s). Kilowatt and megawatt scale to home appliances, motors, and power plants.
Automotive HP
Mechanical horsepower = 745.7 W (US/UK car spec sheets). Metric horsepower (PS) = 735.5 W (German/Japanese cars). Convert kW ↔ hp for spec comparisons.
HVAC BTU/hr
BTU per hour is the standard rating for air conditioners, furnaces, and heat pumps. 1 ton of cooling = 12,000 BTU/hr = 3.517 kW.
Electrical HP
Electrical horsepower = 746 W exactly. Used for electric motor nameplate ratings in the US.
Live Conversion
Result updates on every keystroke. Quickly compare a 200 kW EV to a 268 hp gas car, or size an HVAC unit in kW from a BTU/hr spec.
100% Private
All math runs in your browser. No data leaves your device.
Free vs Pro
| Feature | Free | Pro |
|---|---|---|
| All 8 power units | ||
| Live conversion | ||
| All-units result table | ||
| Bulk CSV / Excel conversion | — | |
| REST API access | — | |
| Custom precision settings | — |
Frequently Asked Questions
It depends. Mechanical (imperial) hp = 745.6999 W. Metric hp (PS) = 735.49875 W. Electrical hp = 746 W exactly. Difference is small (~1.4%) but matters for engine spec comparisons.
Kilowatt (kW) is power — the rate of energy use. Kilowatt-hour (kWh) is energy — power × time. A 1 kW kettle running for 1 h uses 1 kWh of energy. Use the Energy Converter for kWh.
Multiply BTU/hr by 0.29307. Example: 12,000 BTU/hr × 0.29307 ≈ 3517 W = 3.517 kW (a "1 ton" AC unit).
Historical: James Watt defined mechanical hp from horse-drawn pumps. Continental Europe rounded to 75 kgf·m/s = metric hp (PS). Engineers later standardized electrical hp as exactly 746 W for motor ratings. Modern SI uses kilowatts everywhere.
Yes — peak panel output is in watts (W) or kilowatts (kW). Daily energy production is kWh. Use this tool for instantaneous power, the Energy Converter for daily/monthly energy.