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Converters

Power Converter

Convert watts, kilowatts, mechanical and metric horsepower, and BTU/h — the units used across engines, PCs, and HVAC.

Watts (W)1
Kilowatts (kW)0.001
Megawatts (MW)0.000001
Horsepower, mechanical (hp)0.001341
Horsepower, metric (PS)0.00136
BTU/hour3.412142

Anchored conversions from Watts (W) use exact internationally agreed factors. Everything is computed locally, instantly.

Horsepower Has Two Definitions — and VA Is Not Watts

Mechanical horsepower is 745.7 W, but metric horsepower (PS, the unit European car specs use) is 735.5 W — a 1.4% gap that explains why the same engine is quoted as 300 hp in the US and 304 PS in Europe. In AC electrical systems, watts measure real power while volt-amperes (VA) measure apparent power; they differ by the power factor, which is why a 1000 VA UPS powers less than 1000 W of equipment. Converting between W and VA without the power factor is the mistake that undersizes installations.

How the Conversion Works

  1. Enter a power value in any unit and see all others convert simultaneously.
  2. Both US mechanical horsepower (745.7 W) and metric horsepower (735.5 W) are distinguished explicitly.
  3. BTU/h links HVAC ratings into electrical terms.
  4. Context hints compare values to familiar appliances.
Formula & Technical Standard
1 hp (mech) = 745.699872 W · 1 hp (metric) = 735.49875 W (exact) · 1 BTU/h = 0.29307107 W.

Conversion Example

Car engine spec
Input: 300 hp (US spec)
Output: 223.7 kW · 304.2 metric hp
US and European spec sheets quote different horsepower definitions for the same engine — both are shown.
Space heater vs AC
Input: 1500 W heater vs 5,100 BTU/h AC
Output: Both ≈ 1.5 kW
Converting BTU/h to watts puts heating and cooling equipment on one comparable scale.

Common Questions

Why are there two horsepowers?

James Watt’s original hp (745.7 W) and the metric PS/CV (735.5 W) developed in parallel. Engines marketed in Europe often quote PS; US specs quote hp.

Is watt-hour a power unit?

No — watt-hour is energy (see the Energy Converter). Watts measure the instantaneous rate.

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