745.7
W
0.7457
kW
0.000746
MW
745.7
W
0.7457
kW
0.000746
MW
The Horsepower to Watts Converter converts power from mechanical horsepower (HP) to watts (W) and kilowatts (kW) using the standard conversion factor 1 HP = 745.7 watts. This conversion is fundamental for translating traditional engine ratings into SI units used in international engineering and electrical specifications.
Horsepower has been the standard unit for rating engines and motors since James Watt introduced it in the late 18th century. Despite the global adoption of the metric system, horsepower remains deeply embedded in automotive culture, industrial equipment catalogs, and regulatory standards in many countries. Converting HP to watts bridges the gap between legacy specifications and modern SI-based engineering.
The conversion is widely needed in several contexts: selecting electric motors to replace combustion engines (requiring equivalent kW ratings), designing hybrid powertrains that combine HP-rated engines with kW-rated electric motors, comparing vehicle specifications across markets (US uses HP, EU uses kW), and calculating electrical requirements for motor-driven industrial equipment.
One mechanical horsepower equals exactly 33,000 foot-pounds per minute, which converts to 745.69987 watts. In practice, 745.7 W is used for most applications. A quick mental approximation is that 1 HP ≈ 3/4 kW, which gives results within 0.6% accuracy — sufficient for rough estimates.
Our converter provides both watts (for precise engineering calculations) and kilowatts (for practical motor and equipment ratings). Whether you are sizing a VFD for a 50 HP motor, calculating the electrical load of an engine-driven pump, or comparing car engines, this tool gives you instant, accurate results.
The formula: watts = HP × 745.7. For kilowatts: kW = HP × 0.7457. The mechanical horsepower is defined as 33,000 ft·lbf/min = 550 ft·lbf/s = 745.69987 W.
Quick references: 1 HP = 745.7 W, 10 HP = 7.457 kW, 100 HP = 74.57 kW, 200 HP ≈ 149 kW, 500 HP ≈ 373 kW. A typical house circuit (15A at 120V) can provide about 1800 W ≈ 2.4 HP.
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200 HP car engine = 149.1 kW
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Results
50 HP motor = 37.3 kW
One mechanical horsepower = 745.7 watts (745.69987 W precisely). Quick estimate: 1 HP ≈ 3/4 kW.
Multiply HP by 0.7457. For example, 100 HP × 0.7457 = 74.57 kW.
Mechanical HP = 745.7 W, electrical HP = 746 W (a difference of 0.04%). For most practical purposes, they are interchangeable.
One HP can lift 550 pounds one foot per second, or 33,000 pounds one foot per minute. It is about the power needed to run a large window air conditioner.
Typical passenger cars range from 100 to 300 HP (75–224 kW). Sports cars may have 400–700 HP, and supercars exceed 1000 HP.
Motor HP depends on flow rate, head pressure, and pump efficiency. The formula is: HP = (GPM × Head in feet) / (3960 × pump efficiency).
Convert HP to watts, add motor efficiency losses, then use Ohm's law (I = P/V) to find current draw. Always include a safety margin and check NEC code requirements.
Motors rated less than 1 HP (under 745.7 W). Common sizes: 1/4 HP (186 W), 1/3 HP (249 W), 1/2 HP (373 W), 3/4 HP (559 W).
No. Metric HP (PS in German, CV in French) = 735.5 W, about 1.4% less than mechanical HP (745.7 W). A 100 HP engine = 101.4 PS.
Naturally aspirated engines lose about 3% HP per 1000 feet of elevation due to lower air density. Turbocharged engines are less affected.
Roboculator Team
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