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Convert Watts to Horsepower - Power Converter

This converter translates power expressed in kilowatts (kW) into horsepower (hp). It is intended for engineers, technicians, and consumers who need a reliable numeric conversion and clear guidance about which horsepower definition is being used.

Horsepower has multiple historical and practical definitions. By default this tool uses the commonly adopted mechanical (international) horsepower definition where 1 hp = 745.699872 watts. The page explains alternative hp definitions, the small numeric differences they produce, and when to select each for regulatory labeling or technical calculations.

Updated Nov 18, 2025

Interactive Converter

Convert between kilowatt and horsepower with precision rounding.

Quick reference table

KilowattHorsepower
1 kW1.341 hp
5 kW6.705 hp
10 kW13.41 hp
25 kW33.526 hp
50 kW67.051 hp
100 kW134.102 hp

Methodology

The conversion uses the fixed mathematical relationship between the watt (SI unit of power) and horsepower definitions. One kilowatt equals 1000 watts, and horsepower is defined as a specific number of watts depending on the horsepower type chosen. No empirical calibration is required for the arithmetic conversion itself.

For trustworthy unit definitions and guidance on unit usage we follow national and international standards and references including NIST guidance on units, the ISO quantities and units series, and IEEE recommendations where unit notation and electrical conventions apply. See citations for authoritative documents.

Users performing measurements for compliance, equipment specification, or lab reporting should consider measurement uncertainty and instrument calibration. The conversion preserves numerical precision but does not reduce measurement uncertainty associated with the source kW value.

Worked examples

Example 1: Convert 10 kW to mechanical horsepower. hp = 10 * 1000 / 745.699872 = 13.4102209 hp, typically reported as 13.41 hp.

Example 2: Convert 10 kW to metric horsepower (PS). hp(PS) = 10 * 1000 / 735.49875 = 13.5962162 PS, typically reported as 13.60 PS.

Example 3: Convert 5 kW using electrical horsepower (746 W). hp(electric) = 5 * 1000 / 746 = 6.7024129 hp, typically reported as 6.70 hp.

Further resources

Expert Q&A

Which horsepower definition does this converter use by default?

The default is the mechanical (international) horsepower where 1 hp = 745.699872 W. This is commonly used in engineering contexts. Alternatives such as electrical horsepower (746 W) and metric horsepower (735.49875 W) are noted and may be selected where appropriate.

Why are there several horsepower values and which should I use for labeling?

Horsepower arose historically in different industries and countries, producing multiple conventions. Use the definition specified by the regulator, manufacturer guidance, or industry standard applicable to your jurisdiction. When in doubt for mechanical equipment, the international mechanical horsepower is widely accepted; for automotive contexts the metric horsepower (PS) is often used.

How precise is the conversion and what about measurement uncertainty?

The arithmetic conversion is exact given the defined constants, but the final reported precision should reflect the uncertainty of the input measurement. If the kW value comes from a meter or sensor, use the instrument's calibration uncertainty to determine appropriate significant digits for the converted hp value.

Can I convert back from horsepower to kilowatts?

Yes. Invert the same relationship: kW = hp * 745.699872 / 1000 for mechanical horsepower. Use the consistent horsepower definition for both directions to avoid mismatches.

Does the converter account for efficiency or losses?

No. This tool performs unit conversion only. When converting rated electrical power to mechanical output or vice versa, you must apply efficiency or loss factors separately based on measured or specified efficiency.

Are there regulatory requirements for reporting power ratings?

Yes. Equipment labeling and performance claims may be governed by regional regulations and industry standards. Ensure compliance with applicable standards and reference bodies such as national metrology institutes and industry-specific codes when publishing rated power.

Sources & citations