Horsepower to Watts Converter

One mechanical horsepower is 745.7 watts:

watts = horsepower × 745.69987

For most purposes 1 hp ≈ 0.75 kW, and the reverse rule — kW × 4/3 = hp — is accurate to within half a percent.

Common ratings:

• 1 hp → 745.7 W
• 10 hp → 7,457 W (7.46 kW)
• 150 hp → 111,855 W (111.9 kW) — a typical family car
• 300 hp → 223,710 W (223.7 kW)
• 500 hp → 372,850 W (372.9 kW)
• 1,000 hp → 745,700 W (745.7 kW)

Electric vehicles make this conversion routine, because EV specifications are in kilowatts and the cars they replace were sold in horsepower. A 150 kW motor is 201 hp; a 300 kW dual-motor setup is 402 hp.

Note the difference between motor power and charging power, which share the unit and mean different things. A 250 kW rapid charger delivers energy into the battery; the car's 200 kW motor takes it back out. Both are "250 kW" and "200 kW" but neither figure constrains the other.

Metric horsepower (PS) is 735.5 W, about 1.4% less than mechanical hp. European manufacturers quote PS, so a "200 PS" car is 147.1 kW, or 197.3 mechanical hp. The gap is why the same model appears with two ratings in different markets.

Power tools are quoted inconsistently: a "2 hp" shop vacuum draws about 1,500 W at the wall, which is 2.0 hp of input — the useful output is far lower once motor efficiency is counted. Peak horsepower claims on consumer tools are rarely sustained figures.