Conversion method
Mechanical horsepower is approximately 745.699872 W; metric horsepower (PS) is 735.49875 W. They are not interchangeable. Power is a rate; multiply kW by hours to obtain kWh of energy.
kW = x × 0.74569987158227
10 hp = 7.456999 kW.
| hp | kW |
|---|---|
| 1 | 0.7457 |
| 5 | 3.728499 |
| 10 | 7.456999 |
| 25 | 18.642497 |
| 50 | 37.284994 |
| 100 | 74.569987 |
Unit definitions and sources
Mechanical horsepower differs from metric horsepower (PS). BTU per hour uses International Table BTU; a ton of refrigeration is exactly 12,000 BTU/h. dBm and dBW are logarithmic levels relative to 1 mW and 1 W, so they require a power greater than zero.
60 of the 68 definitions below were checked against the cited sources on 2026-09-20 (AI-assisted check).
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Watt (W); si | Common units | Watt measures power. w = (value in W) × 1. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilowatt (kW); si | Common units | Kilowatt measures power. w = (value in kW) × 1000. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Megawatt (MW); si | Common units | Megawatt measures power. w = (value in MW) × 1000000. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Horsepower (mechanical) (hp); us | Common units | Horsepower (mechanical) measures power. w = (value in hp) × 745.6998715822702. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| BTU per hour (BTU/h); us | Common units | BTU per hour measures power. w = (value in BTU/h) × 0.2930710701722222. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Metric horsepower (PS); metric | Specialist units | Metric horsepower measures power. w = (value in PS) × 735.49875. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Foot-pound per second (ft·lbf/s); us | Specialist units | Foot-pound per second measures power. w = (value in ft·lbf/s) × 1.3558179483314003. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie per hour (kcal/h); other | Specialist units | Kilocalorie per hour measures power. w = (value in kcal/h) × 1.1622222222222223. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Ton of refrigeration (TR); us | Specialist units | Ton of refrigeration: exactly 12,000 BTU (IT) per hour = 12,000 × 1055.05585262 J ÷ 3600 s = 3516.852842066… W. Common use: Air-conditioner and chiller cooling capacity. A refrigeration ton is a cooling rate (12,000 BTU/h), not a mass; it is unrelated to the short, long or metric ton. | Exact definition; numerical display may be rounded |
| Decibel-milliwatt (dBm); other | Specialist units | dBm is a power level relative to 1 mW: P(W) = 0.001 × 10^(dBm/10); dBm = 10 × log10(P / 1 mW). Common use: Radio, fibre and RF signal power levels. dBm is a logarithmic level, not a linear unit: 0 dBm = 1 mW, 30 dBm = 1 W, negative dBm is below 1 mW, and zero or negative power has no dBm value. | Exact definition; numerical display may be rounded |
| Decibel-watt (dBW); other | Specialist units | dBW is a power level relative to 1 W: P(W) = 10^(dBW/10); dBW = 10 × log10(P / 1 W) = dBm − 30. Common use: Transmitter and satellite link power levels. dBW is a logarithmic level relative to 1 W: 0 dBW = 1 W = 30 dBm; zero or negative power has no dBW value. | Exact definition; numerical display may be rounded |
| Exawatt (EW); si | Specialist units | exawatt: E denotes 10^18; the unit gives 1000000000000000000 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Petawatt (PW); si | Specialist units | petawatt: P denotes 10^15; the unit gives 1000000000000000 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Terawatt (TW); si | Specialist units | terawatt: T denotes 10^12; the unit gives 1000000000000 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Gigawatt (GW); si | Specialist units | gigawatt: G denotes 10^9; the unit gives 1000000000 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Hectowatt (hW); si | Specialist units | hectowatt: h denotes 10^2; the unit gives 100 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Decawatt (daW); si | Specialist units | decawatt: da denotes 10^1; the unit gives 10 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Deciwatt (dW); si | Specialist units | deciwatt: d denotes 10^-1; the unit gives 0.1 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Centiwatt (cW); si | Specialist units | centiwatt: c denotes 10^-2; the unit gives 0.01 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Milliwatt (mW); si | Specialist units | milliwatt: m denotes 10^-3; the unit gives 0.001 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Microwatt (µW); si | Specialist units | microwatt: µ denotes 10^-6; the unit gives 0.000001 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Nanowatt (nW); si | Specialist units | nanowatt: n denotes 10^-9; the unit gives 1e-9 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Picowatt (pW); si | Specialist units | picowatt: p denotes 10^-12; the unit gives 1e-12 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Femtowatt (fW); si | Specialist units | femtowatt: f denotes 10^-15; the unit gives 1e-15 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Attowatt (aW); si | Specialist units | attowatt: a denotes 10^-18; the unit gives 1e-18 w. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Btu (IT)/hour (BTU IT/(h)); other | Specialist units | Btu (IT)/hour = 0.2930710701722222 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Btu (IT)/minute (BTU IT/(min)); other | Specialist units | Btu (IT)/minute = 17.584264210333334 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Btu (IT)/second (BTU IT/(s)); other | Specialist units | Btu (IT)/second = 1055.05585262 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Btu (th)/hour (BTU th/(h)); other | Specialist units | Btu (th)/hour = 0.29287507346913577 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Btu (th)/minute (BTU th/(min)); other | Specialist units | Btu (th)/minute = 17.572504408148145 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Btu (th)/second (BTU th/(s)); other | Specialist units | Btu (th)/second = 1054.3502644888888 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie (IT)/hour (kcal IT/(h)); other | Specialist units | kilocalorie (IT)/hour = 1.163 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie (IT)/minute (kcal IT/(min)); other | Specialist units | kilocalorie (IT)/minute = 69.78 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie (IT)/second (kcal IT/(s)); other | Specialist units | kilocalorie (IT)/second = 4186.8 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie (th)/hour (kcal th/(h)); other | Specialist units | kilocalorie (th)/hour = 1.1622222222222223 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie (th)/minute (kcal th/(min)); other | Specialist units | kilocalorie (th)/minute = 69.73333333333333 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilocalorie (th)/second (kcal th/(s)); other | Specialist units | kilocalorie (th)/second = 4184.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Calorie (IT)/hour (cal IT/(h)); other | Specialist units | calorie (IT)/hour = 0.001163 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Calorie (IT)/minute (cal IT/(min)); other | Specialist units | calorie (IT)/minute = 0.06978 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Calorie (IT)/second (cal IT/(s)); other | Specialist units | calorie (IT)/second = 4.1868 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Calorie (th)/hour (cal th/(h)); other | Specialist units | calorie (th)/hour = 0.0011622222222222223 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Calorie (th)/minute (cal th/(min)); other | Specialist units | calorie (th)/minute = 0.06973333333333334 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Calorie (th)/second (cal th/(s)); other | Specialist units | calorie (th)/second = 4.184 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Foot pound-force/hour (ft·lbf/(h)); other | Specialist units | foot pound-force/hour = 0.0003766160967587223 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Foot pound-force/minute (ft·lbf/(min)); other | Specialist units | foot pound-force/minute = 0.02259696580552334 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilovolt ampere (kV·A); other | Specialist units | kilovolt ampere = 1000.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Volt ampere (V·A); other | Specialist units | volt ampere = 1.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Newton meter/second (N·m/(s)); other | Specialist units | newton meter/second = 1.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Joule/second (J/(s)); other | Specialist units | joule/second = 1.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Exajoule/second (EJ/(s)); other | Specialist units | exajoule/second = 1e+18 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Petajoule/second (PJ/(s)); other | Specialist units | petajoule/second = 1000000000000000.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Terajoule/second (TJ/(s)); other | Specialist units | terajoule/second = 1000000000000.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Gigajoule/second (GJ/(s)); other | Specialist units | gigajoule/second = 1000000000.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Megajoule/second (MJ/(s)); other | Specialist units | megajoule/second = 1000000.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilojoule/second (kJ/(s)); other | Specialist units | kilojoule/second = 1000.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Hectojoule/second (hJ/(s)); other | Specialist units | hectojoule/second = 100.0 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Decijoule/second (dJ/(s)); other | Specialist units | decijoule/second = 0.1 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Centijoule/second (cJ/(s)); other | Specialist units | centijoule/second = 0.01 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Millijoule/second (mJ/(s)); other | Specialist units | millijoule/second = 0.001 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Microjoule/second (µJ/(s)); other | Specialist units | microjoule/second = 1e-06 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Nanojoule/second (nJ/(s)); other | Specialist units | nanojoule/second = 1e-09 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Picojoule/second (pJ/(s)); other | Specialist units | picojoule/second = 1e-12 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Femtojoule/second (fJ/(s)); other | Specialist units | femtojoule/second = 1e-15 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Attojoule/second (aJ/(s)); other | Specialist units | attojoule/second = 1e-18 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Joule/hour (J/(h)); other | Specialist units | joule/hour = 0.0002777777777777778 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Joule/minute (J/(min)); other | Specialist units | joule/minute = 0.016666666666666666 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilojoule/hour (kJ/(h)); other | Specialist units | kilojoule/hour = 0.2777777777777778 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
| Kilojoule/minute (kJ/(min)); other | Specialist units | kilojoule/minute = 16.666666666666668 w, derived from the component SI/customary definitions. Common use: Rate of energy transfer. | Exact definition; numerical display may be rounded |
Sources: BIPM: International System of Units; NIST: SP 811 Appendix B.8: conversion factors; ITU: ITU-R V.574: Use of the decibel and the neper in telecommunications; NIST: SP 811 Chapter 8: logarithmic quantities and units; BIPM: SI prefixes
Precision of power conversions
All 68 power units convert through Watt (W). 68 have an exact defined relationship to the base unit and 0 are conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.