What this calculator does
Convert power between watts, horsepower, BTU per hour, and foot-pounds per second.
How it works
The calculator evaluates watts = value × watts-per-source-unit; result = watts ÷ watts-per-target-unit. Inputs are checked before calculation, and invalid values such as zero denominators or out-of-range selections produce a clear error instead of a misleading result.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?value=PowerNumber · Required · Default: 1
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?fromUnit=From unitChoice · Required · Default: hp · Accepted values: W, kW, MW, hp, hpMetric, BTUh, ftlbs
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?toUnit=To unitChoice · Required · Default: kW · Accepted values: W, kW, MW, hp, hpMetric, BTUh, ftlbs
Outputs
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resultConverted powerNumber · Primary output
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wattsEquivalent wattsNumber
Inputs and results
The inputs are Power, From unit, To unit. Results include Converted power, Equivalent watts.