Power Converter
Convert between watts, kilowatts, megawatts, horsepower and BTU per hour.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
1 kW ≈ 1.3410220896 hp
About this calculator
Power is energy per unit time. The mechanical horsepower was defined by James Watt as 550 foot-pounds per second, which works out to about 745.7 watts.
Worked example
calculated with the default values below
Value 1 · From Mechanical horsepower · To Kilowatts (kW) · Decimal places 4 Result 0.7457 · Watts 745.70 W · Kilowatts 0.745700 kW · Mechanical horsepower 1.0000 hp
Method and assumptions
Formula basis and scope
Convert power via watts; mechanical horsepower and metric horsepower use different factors.
Only the displayed unit definitions are converted; rounding and measurement uncertainty are separate.
Data sources
Disclaimer
These calculators give general conversion results. Rounding and the precision of the value you enter both affect the output, so treat displayed decimals as indicative rather than exact.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
result = v · F[s] ÷ F[t]
- result
- Converted value
- v
- Value in source unit
- F
- Unit factor table (see note)
- s
- Source unit code
- t
- Target unit code
F table: W 1, kW 1000, MW 10^6, hp 745.6999, metric hp 735.4988, BTU/h 0.2931, refrigeration ton 3516.85.
Frequently asked questions
Why is a metric horsepower smaller than a mechanical one?
The tool carries both: mechanical hp is 745.7 watts while metric hp (PS) is 735.5 watts, so 1 mechanical hp equals about 1.014 metric hp. A ton of refrigeration is 3,516.85 W and one BTU per hour is 0.293 W, so converting 1 hp to kW gives 0.7457 and the result field re-derives it through watts as the common base. Picking hpmetric instead of hp in the From menu therefore lowers the watt reading by about 1.4%.