Power Converter: Watts, kW, Horsepower, BTU/h, AC Tons
Convert watts, kilowatts, US and metric horsepower, BTU per hour and tons of refrigeration.
Inputs
| Unit | 1 Horsepower (US) is |
|---|---|
| Watt | 745.6999 |
| Kilowatt | 0.7457 |
| Horsepower (US) | 1 |
| Horsepower (metric) | 1.01387 |
| BTU/hour | 2,544.433416 |
| Ton of refrigeration | 0.212036 |
- Factor
- 1 Horsepower (US) = 0.7457 Kilowatt
- Working
- 1 × 0.7457 = 0.7457
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What each Power input means
- Value
- The power to convert: an engine, a motor, a heater, an air conditioner. Power is a rate — energy per second — not an amount of energy.
- From
- Watts and kilowatts are SI; horsepower (US, 550 ft·lbf/s) and metric horsepower (PS) are engine ratings; BTU per hour and tons of refrigeration are heating and cooling capacities.
- To
- The unit you want. The table under the answer lists all six at once.
Power conversion formula
result = value × (watts in one 'from' unit ÷ watts in one 'to' unit) · 1 hp = 745.7 W
Power is energy per second, measured in watts. Mechanical horsepower, used for US engines, is 550 foot-pounds a second — 745.7 W. European 'PS' or metric horsepower is 735.5 W, 1.4% less. Air-conditioner capacity is quoted in BTU per hour, or in tons of refrigeration: one ton is 12,000 BTU an hour, 3.517 kW of cooling. The page converts through watts and lists every unit.
Power conversion worked example
1 hp = 0.7457 kW, so a 300 hp engine is 223.7 kW, and 1 kW is 1.341 hp. A 2-ton air conditioner moves 24,000 BTU of heat an hour — 7.03 kW of cooling.
More Power examples
A 150 kW engine: 150 × 1.341022 = 201.153306 hp — or 204 metric horsepower, the PS figure on European spec sheets.
A 12,000 BTU/h air conditioner: 12,000 × 0.0002930711 = 3.516853 kW of cooling — one ton of refrigeration.
One metric horsepower (PS) is 735.4988 W, about 10 W less than a US horsepower.
Where the Power converter can give the wrong answer
- Check which horsepower a spec sheet means: US hp (745.7 W), metric PS (735.5 W) and the 746 W electrical horsepower differ slightly.
- An air conditioner's cooling capacity (BTU/h or tons) is not the electricity it draws; that is lower, by its efficiency ratio.
- Power is a rate. Multiply by time for energy: 1 kW for 1 hour is 1 kWh.
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Power conversion reference table
| Horsepower (US) | Kilowatts | Metric horsepower (PS) |
|---|---|---|
| 1 | 0.75 | 1.01 |
| 5 | 3.73 | 5.07 |
| 100 | 74.57 | 101.39 |
| 150 | 111.85 | 152.08 |
| 200 | 149.14 | 202.77 |
| 300 | 223.71 | 304.16 |
| 400 | 298.28 | 405.55 |
| 500 | 372.85 | 506.93 |
Power conversion FAQ
- Multiply by 0.7457. 150 hp is 111.9 kW.
- Multiply by 1.341. A 100 kW motor is 134.1 hp.
- 12,000 BTU per hour of cooling, which is 3.517 kW. A 3-ton system is 36,000 BTU/h.
- PS is metric horsepower, 735.5 W; US hp is 745.7 W. A 200 PS engine is 197.3 hp.
- 745.7 W for US (mechanical) horsepower, 735.5 W for metric horsepower. The two differ by about 1.4%.
- No. A kilowatt is power, a rate; a kilowatt-hour is energy, the amount used. A 2 kW heater running for 3 hours uses 6 kWh.
- 12,000 BTU per hour is one ton of refrigeration, 3.52 kW of cooling. 24,000 BTU/h is two tons, 7.03 kW.
- 134.1 US horsepower, or 136 metric horsepower (PS).
- Multiply by 0.2931: a 5,000 BTU/h window air conditioner gives 1,465 W of cooling. That is cooling capacity, not the electricity it draws, which is lower.
- 17.6 kW of cooling: 5 × 3.517. Tons here are tons of refrigeration, not weight.
- Engine power measured at the crankshaft, before the gearbox and drivetrain take their share; power at the wheels is lower. Either can be converted here — the units are the same.
- Multiply by time. A 2 kW heater for 3 hours uses 6 kWh; the energy converter turns that into joules, BTU or kilocalories.
- 1.34 hp: 1,000 ÷ 745.7.
- 3,412 BTU/h. A 3.5 kW air conditioner is about 12,000 BTU/h, one ton.
- 1,000. A 2.5 kW kettle draws 2,500 W.
- 223.7 kW: 300 × 0.7457.
- It is defined as 75 kilogram-force metres per second, 735.5 W, while US horsepower is 550 foot-pounds-force per second, 745.7 W.
- 0.7457 kW for a US horsepower.
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