Convert horsepower and kilowatts both ways, choose the correct horsepower type, and see the exact factor used so you do not mix unit standards.
Advanced options
Table of contents
How to use our Horsepower to kW Converter
- Choose Convert to match the unit you are starting with: horsepower to kilowatts or kilowatts to horsepower.
- Select the correct Horsepower type. Use mechanical horsepower for common US engine ratings, metric horsepower for some European vehicle specs, and electric horsepower for some technical motor references.
- Enter the Power value, then pick Decimal places if you want more or less rounding.
- Click Calculate and read Converted power, Conversion factor used, Horsepower type note, and Formula used.
- Sanity-check the answer by confirming the type note matches your source and that 100 hp converts to about 74 to 75 kW for mechanical or electric hp, but about 73.5 kW for metric hp.
Definitions
Horsepower type: The specific horsepower standard used in the conversion. Mechanical, metric, and electric horsepower are close in size but not identical.
Mechanical horsepower (US): A common US horsepower standard used for many engine ratings. In this calculator, 1 mechanical hp = 0.7456998715822702 kW.
Metric horsepower: A horsepower standard often linked with vehicle specs in metric contexts. In this calculator, 1 metric hp = 0.73549875 kW.
Electric horsepower: A horsepower standard defined from electrical power. In this calculator, 1 electric hp = 0.746 kW.
Kilowatt (kW): A metric unit of power equal to 1,000 watts [1].
Conversion factor used: The exact number multiplied or divided by your starting value to get the converted result.
Formula used: The equation applied for the selected direction and horsepower type.
Common mistakes and quick fixes
Mistake: Leaving Horsepower type on the wrong setting and converting a value from a different standard.
Fix: Match Horsepower type to the original spec before trusting Converted power .
Mistake: Entering kW in Power value while Convert is still set to horsepower to kilowatts.
Fix: Set Convert to the direction that matches the unit you start with, then recheck Formula used .
Mistake: Typing letters or leaving Power value blank.
Fix: Enter only a real number in Power value , such as 75, 100, or 0.746.
Mistake: Thinking all horsepower values give the same result because the numbers look close.
Fix: Compare the Conversion factor used for mechanical, metric, and electric types before using the result in a report or part selection.
Mistake: Rounding too early and then getting a slightly different Converted power by hand.
Fix: Increase Decimal places and use the displayed Conversion factor used for any manual check.
Mistake: Assuming a negative Converted power is always an error.
Fix: If your Power value was negative, the sign is kept on purpose; for most equipment ratings, enter a positive value instead.
Limitations & Key Assumptions / Boundary Conditions
- This converter only handles the three listed horsepower standards: mechanical horsepower (US), metric horsepower, and electric horsepower.
- Results depend on choosing the correct Horsepower type. If the original source uses a different standard or does not say which one, the result can be off.
- The calculator converts units only. It does not estimate real motor output, drivetrain losses, torque, efficiency, or test-condition differences.
- Displayed values are rounded to the selected Decimal places, even though the stored factor is more precise.
- Negative inputs are allowed so signed power differences can be converted, but most real equipment ratings are positive.
- Very large values are formatted for readability, but the meaning of the result is still only as good as the original unit label and horsepower standard.
Methodology
How the conversion works
The calculator first reads the selected Convert direction and Horsepower type. It then uses the matching exact factor for that horsepower standard.
kW = hp_mechanical x 0.7456998715822702
hp_mechanical = kW / 0.7456998715822702
kW = hp_metric x 0.73549875
hp_metric = kW / 0.73549875
kW = hp_electric x 0.746
hp_electric = kW / 0.746
Factors used
Mechanical horsepower uses 745.6998715822702 watts per hp, metric horsepower uses 735.49875 watts per hp, and electric horsepower uses 746 watts per hp. Since 1 kilowatt equals 1,000 watts [1], the calculator converts these to kW-per-hp factors by dividing by 1,000.
Worked example
If Convert is horsepower to kilowatts, Horsepower type is mechanical, and Power value is 100, the calculation is:
kW = 100 x 0.7456998715822702 = 74.56998715822702
With 3 decimal places, Converted power displays as 74.570 kW.
If you switch to kilowatts to horsepower with the same mechanical standard and enter 75 kW, the calculation is:
hp = 75 / 0.7456998715822702 = 100.576656
With 3 decimal places, the display becomes 100.577 hp.
Calculation choices
The sign of the input is preserved, so a negative Power value gives a negative Converted power. Zero converts to zero. Blank text, non-numeric text, NaN, and Infinity are rejected as input errors instead of being treated as zero.
Assumptions used
This tool assumes the input value is already a power value in the selected starting unit and that the selected horsepower standard matches the original source. Real-world published ratings can still differ because of rounding, labeling practice, or the source using a different horsepower definition [4].