Power Converter
Power Converter — runs in your browser. Inputs are not stored.
Power unit conversion
Enter values, then press Calculate.
1 metric HP ≈ 735.49875 W, 1 mechanical HP ≈ 745.699872 W.
How to use
- Enter a value and choose a unit. The default is 1 watt.
- Units are W, kW, MW, mW, metric HP, mechanical HP, and BTU/h.
- Press Convert or change value/unit to refresh every power figure.
- Check the spec sheet for whether a motor nameplate HP is metric or mechanical, then read that row.
- Reset restores 1 W. For voltage–current relationships, use the electrical unit converter.
Key concepts
The SI unit of power is the watt (W). 1 kW = 1000 W, 1 MW = 10^6 W, 1 mW = 0.001 W. Horsepower definitions split: this tool’s metric HP is about 735.49875 W and mechanical HP about 745.699872 W. BTU/h used in HVAC and boilers is about 0.29307107 W. The table redraws as you type or change unit. mW is for electronics and MW for generation scale—watch the digits even on one table. The two horsepower rows are split on purpose.
Finding watts from V, A, and Ω in a circuit is different from converting watts you already have into horsepower. The former is the electrical unit converter; the latter is this screen. Engine output and electric-motor nameplates often use different HP, so both rows are shown. Car PS/HP labels vary by region, so the ~735 W and ~746 W rows sit together. Use the table to match HVAC catalogue BTU/h to watts. You only need a power number, not voltage.
Example
1 metric HP is about 735.5 W, about 0.7355 kW. 1 mechanical HP is a little larger, about 745.7 W. 1000 W is 1 kW, about 1.36 metric HP, about 3412 BTU/h. A 3 kW heater is on the order of 10,236 BTU/h. A 2 metric HP motor is about 1471 W. A 1500 W heater is about 2.04 metric HP, about 5118 BTU/h. 5 MW is 5000 kW.
Related: Electrical unit converter · Engineering unit converter
Frequently asked questions
What is the difference among W, kW, and horsepower in the power converter?
W and kW are related by powers of 10. Horsepower is a historical unit treated as 735.5 W or 745.7 W per 1 HP. The same 10 HP is about 7.35 kW metric or about 7.46 kW mechanical. Check the nameplate unit first.
Should I use metric HP or mechanical HP?
Much of Europe and some cars use metric; US machinery often uses mechanical. Follow the nameplate or manual. For Korean car catalogues’ PS, read the metric row. US engine brochures are often mechanical.
Is BTU/h converted too?
Yes. 1 BTU/h ≈ 0.29307107 W. Use it to compare heating/cooling capacity with watts. The BTU/h row bridges boiler capacity and electric-heater watts.
Where do I see V–A relationships for a circuit?
The electrical unit converter’s V·A·Ω·W mode. This page only changes units of power you already have. Do not size a breaker from this number alone if you do not know the current.
Does MW (megawatt) appear too?
Yes. Generation and industrial-scale figures can be seen together on the kW and MW rows. mW is for electronics standby. Solar-inverter kW and generator kVA are different. This table is the active-power watt family.
Do conversion results update live?
They recalculate as soon as you type a value or change unit, same as the Convert button. Decimal input applies immediately, so switch units to match spec wording.
Last reviewed: 2026-09-04