Conversion Runs locally Ready to use Built-in examples No tracking

Power Converter

Convert power between metric and imperial units using definition-based factors.

A car is sold on horsepower, an appliance on watts, a power station on megawatts — power units span daily life and engineering. This tool converts between W, kW, MW, metric horsepower (PS), mechanical horsepower (hp) and foot-pounds per second; the anchors are 1 PS ≈ 735.5 W and 1 hp ≈ 745.7 W — the two horsepowers are not equal, differing by about 1.4%.

On conventions: European and Japanese cars mostly quote PS while American cars quote hp, so the same number is larger in hp; a motor's nameplate kW is its rated output, and sizing switchgear wants headroom on top of that; and the "ton" of air-conditioning is about 735 W of input power, with the cooling capacity quoted separately — two different numbers that are best not mixed.

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How to use

  1. Enter the power and choose its unit.
  2. Read the value in the other units.
  3. Check whether a horsepower figure is metric or mechanical.
  4. Keep input power and cooling capacity apart for air-conditioning.

How it works

Power conversion factors

Power = work / time; the SI unit, the watt (W), is 1 joule per second. Based on the watt: 1 kW = 1000 W, 1 MW = 1000 kW — so conversion is a single multiply or divide, and precision depends on whether the factor is a defined value.

Metric vs. mechanical horsepower

There are two horsepowers: metric PS = 75 kgf·m/s = 735.49875 W, from metric gravity units; mechanical hp = 550 ft·lbf/s = 745.7 W, from imperial units. They differ by about 1.4% — car specs mostly use PS, Anglo-American material uses hp, so unify before comparing.

Common power magnitudes

Common magnitudes: a 220 V 10 A household socket is about 2.2 kW, 16 A about 3.5 kW; a 1-horsepower air conditioner draws about 735 W of input power (its cooling capacity is about 2500 W — don't conflate them); a car's 100 kW is about 136 metric horsepower.

Code example

JavaScript Metric and imperial horsepower kept apart 

const W = { W: 1, kW: 1e3, MW: 1e6,
            PS: 735.49875, hp: 745.699872, fps: 1.35582 };

const convert = (v, from, to) => v * W[from] / W[to];

convert(100, "kW", "PS");    // 135.96
convert(100, "kW", "hp");    // 134.10 (imperial hp is smaller)

Python The same coefficients in Python 

W = {"W": 1, "kW": 1e3, "PS": 735.49875, "hp": 745.699872}

convert = lambda v, f, t: v * W[f] / W[t]

convert(150, "PS", "kW")   # 110.3
convert(1, "PS", "W") if False else 735   # an air-conditioner "1 hp" draws ≈ 735W

FAQ

What's the difference between metric and mechanical horsepower?

Metric PS = 75 kgf·m/s = 735.49875 W, metric units; mechanical hp = 550 ft·lbf/s = 745.7 W. At the same number, hp is larger by about 1.4%. Car specs mostly use metric horsepower; Anglo-American sources use hp.

Is a "1-horsepower AC" 735 watts?

Not the same thing. An air conditioner's "horsepower" refers to cooling capacity, about 2500 W of cooling for 1 hp, while its input power is usually 735-800 W. Check the nameplate's rated cooling capacity and input power; don't mix them.

How do kW and horsepower convert in car specs?

1 kW is about 1.36 metric horsepower, 100 kW about 136 PS; conversely 1 PS is about 0.7355 kW. Convert both to kW or both to PS before comparing, to avoid being misled by the numbers' look.

How much power can a household socket carry?

Power = voltage x current: 220 V x 10 A is about 2200 W, x 16 A about 3520 W. High-power appliances like ACs, ovens and water heaters should use 16 A sockets on a dedicated circuit — several large loads sharing one circuit can trip breakers or overheat.

What's the difference between kW and kWh?

kW is power (how fast); kWh is energy (how much is used). A 1000 W appliance for 1 hour is 1 kWh, one electricity unit; a 2000 W appliance for half an hour is also 1 kWh. Electricity bills use kWh.

Is the power on a motor nameplate its consumption?

Usually the output mechanical power. Actual consumption = output / efficiency: at 90% efficiency, 1 kW output needs about 1.11 kW input. Power factor and load ratio also matter — the nameplate value is at rated conditions.

Does conversion need a network connection?

No. Power conversion is one multiply or divide, working offline once the page loads. Inputs aren't sent to any server; history stays in local browser storage and can be cleared anytime.