Power Converter
Watts, kilowatts, megawatts, mechanical and metric horsepower, and BTU per hour.
Power Converter
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Units in this category
| Unit | Symbol | Exactly |
|---|---|---|
| watts (W) | W | reference unit for this category |
| kilowatts (kW) | kW | 1,000 W |
| megawatts (MW) | MW | 1,000,000 W |
| mechanical horsepower (hp) | hp | 745.7 W |
| metric horsepower (PS) | PS | 735.499 W |
| BTUs per hour (BTU/h) | BTU/h | 0.29307107 W |
Where these factors come from
Mechanical horsepower is exactly 745.699872 W (550 ft·lbf/s); metric horsepower (PS) is exactly 735.49875 W. Engine and appliance ratings convert cleanly between the two.
All 30 power pairs
| from → to | W | kW | MW | hp | PS | BTU/h |
|---|---|---|---|---|---|---|
| W (watt) | — | 0.001 | 0.000001 | 0.0013410221 | 0.0013596216 | 3.412142 |
| kW (kilowatt) | 1,000 | — | 0.001 | 1.341022 | 1.359622 | 3,412.14 |
| MW (megawatt) | 1,000,000 | 1,000 | — | 1,341.02 | 1,359.62 | 3,412,141.63 |
| hp (mechanical horsepower) | 745.7 | 0.74569987 | 0.0007456999 | — | 1.01387 | 2,544.43 |
| PS (metric horsepower) | 735.499 | 0.73549875 | 0.0007354987 | 0.98632007 | — | 2,509.63 |
| BTU/h (BTUs per hour) | 0.29307107 | 0.0002930711 | 0.0000002931 | 0.0003930148 | 0.0003984658 | — |
Conversions by starting unit
watts (W)
W to kWW to MWW to hpW to PSW to BTU/h
kilowatts (kW)
kW to WkW to MWkW to hpkW to PSkW to BTU/h
megawatts (MW)
MW to WMW to kWMW to hpMW to PSMW to BTU/h
mechanical horsepower (hp)
hp to Whp to kWhp to MWhp to PShp to BTU/h
metric horsepower (PS)
PS to WPS to kWPS to MWPS to hpPS to BTU/h
BTUs per hour (BTU/h)
BTU/h to WBTU/h to kWBTU/h to MWBTU/h to hpBTU/h to PS
Common questions
Is horsepower the same everywhere?
No. Mechanical (imperial) horsepower is exactly 745.699872 W while metric horsepower (PS, used in Europe and Japan) is exactly 735.49875 W — about 1.4% apart. The dedicated hp↔PS page shows the difference.
Why are air conditioners rated in BTU/h?
BTU per hour is a cooling-rate unit from the imperial era. One BTU/h is about 0.293 W, so a 12,000 BTU/h unit is roughly 3.5 kW.
How do I convert engine kW to horsepower?
Multiply kilowatts by 1.34102 for mechanical horsepower, or by 1.35962 for metric PS. Both pages carry tables of common engine ratings.