Converter Tools
Power Converter
Convert power between watts, kilowatts, mechanical and metric horsepower, BTU per hour, tons of refrigeration, kcal/h, and ft-lbf/s in your browser.
Quick conversions
Common engine, HVAC, and appliance power readings.
From unit
Metric / SI
Watts, kW, MW, GW, J/s
Horsepower
Mechanical, metric (PS), electric, boiler, ft-lbf/s
Thermal / HVAC
BTU/h, BTU/min, kBTU/h, tons, kcal/h, kcal/s, cal/s
Other
CGS unit erg/s for astrophysics and physics literature
Decimal places
Show units
Headline
Kilowatts
100 kW
SI standard.
Mechanical horsepower
134.1022 hp
US automotive default.
Metric horsepower
135.9622 PS
Europe and Japan (also CV).
BTU per hour
341214.1633 BTU/h
HVAC default.
Metric / SI
Watts, kilowatts, megawatts, and gigawatts cover almost every modern electrical, mechanical, and industrial spec sheet.
Converted
Watts
100000 W
SI base unit. One joule per second. The default in almost every modern electrical and engineering spec.
Example: 10 W is a typical LED bulb
Converted
Milliwatts
100000000 mW
One thousandth of a watt. Used in radio output, optical sensors, and low-power electronics datasheets.
Example: 1 W = 1000 mW
Source
Kilowatts
100 kW
Thousand watts. Standard for appliances, EV motors, household solar arrays, kettles, and water heaters.
Example: A typical hair dryer is around 1.8 kW
Converted
Megawatts
0.1 MW
Million watts. Used for power-plant output, large industrial loads, and utility-scale solar and wind farms.
Example: A large gas turbine is around 200 MW
Converted
Gigawatts
0.0001 GW
Billion watts. Country-level demand and the output of large nuclear or hydro stations.
Example: 1 GW = 1,000,000,000 W
Converted
Joules per second
100000 J/s
Energy rate in SI. One J/s equals one watt by definition.
Example: 1 J/s = 1 W exactly
Horsepower family
Mechanical hp (US auto), metric PS / CV (Europe and Japan), electric hp (NEMA motors), boiler hp (ASME), and ft-lbf/s (legacy mechanical work rate).
Converted
Mechanical horsepower
134.1022 hp
Also written hp (I) or imperial horsepower. The dominant unit in US automotive engine ratings. 1 hp = 550 ft-lbf/s.
Example: 300 hp is a typical sports sedan engine
Converted
Metric horsepower
135.9622 PS
Also called PS (Pferdestaerke) or CV. Used on European and Japanese spec sheets. 1 PS = 75 kgf-m/s exactly = 735.49875 W.
Example: 200 PS is around 197.2 hp (mechanical)
Converted
Electric horsepower
134.0483 hp(E)
NEMA rating for electric motors, defined as exactly 746 W. Used on US industrial motor name plates.
Example: 1 hp(E) electric motor draws at least 746 W input
Converted
Boiler horsepower
10.1942 hp(S)
ASME boiler horsepower. Defined as the power to evaporate 34.5 lb of water at 212 F per hour, about 9.8095 kW.
Example: 1 hp(S) = 9809.5 W
Converted
Foot-pounds per second
73756.2149 ft-lbf/s
Mechanical work rate. 550 ft-lbf/s defines one mechanical horsepower.
Example: 550 ft-lbf/s = 1 hp
Thermal / HVAC
BTU/h is the standard for cooling, heating, and air conditioning capacity in the US. 1 ton of refrigeration = 12,000 BTU/h exactly.
Converted
BTU per hour
341214.1633 BTU/h
British Thermal Unit per hour (International Table). The default unit for HVAC, heating, and cooling capacity in the US and parts of Asia.
Example: A 1 ton air conditioner is 12,000 BTU/h
Converted
BTU per minute
5686.9027 BTU/min
Sixty times BTU/h. Sometimes seen on combustion-engine and industrial-burner spec sheets.
Example: 1 BTU/min = 17.584 W
Converted
Thousand BTU per hour
341.2142 kBTU/h
Thousand BTU/h. Used on furnaces, boilers, and large commercial HVAC equipment.
Example: 100 kBTU/h is a typical residential furnace
Converted
Tons of refrigeration
28.4345 TR
Cooling capacity equal to 12,000 BTU/h, or about 3.517 kW. The default unit for AC and chiller sizing in North America.
Example: A 3 ton AC is 36,000 BTU/h, around 10.55 kW
Converted
Kilocalories per hour
85984.5228 kcal/h
Common in European HVAC, water-heating, and exercise equipment readouts. 1 kcal/h = 1.163 W exactly.
Example: 1 kcal/h = 1.163 W exact
Converted
Kilocalories per second
23.9006 kcal/s
Used in sports science and nutrition modelling. Treats food kcal (thermochemical, 4184 J) per second.
Example: 0.1 kcal/s burn rate is about 418 W of metabolic output
Converted
Calories per second
23884.5897 cal/s
Lower-case calorie (1 cal_IT = 4.1868 J). Used in physical chemistry and thermodynamics texts.
Example: 1 cal/s = 4.1868 W
Other
The erg per second is a CGS unit, still seen in astrophysics literature for stellar luminosity.
Converted
Ergs per second
1000000000000 erg/s
CGS unit. 1 erg = 1e-7 J. Common in astrophysics literature (stellar luminosity in erg/s).
Example: 1 W = 1e7 erg/s
Common conversions, in plain English
- 1 kW is about 1.341 mechanical hp, or 1.3596 metric PS.
- 1 mechanical hp is exactly 550 ft-lbf/s, about 745.7 W.
- 1 metric horsepower (PS / CV) is exactly 75 kgf-m/s, about 735.5 W.
- 1 NEMA electric hp is defined as exactly 746 W.
- 1 boiler hp (ASME) is 9809.5 W, about 33,475 BTU/h.
- 1 kW is about 3,412 BTU/h.
- 1 ton of refrigeration is exactly 12,000 BTU/h, about 3.517 kW.
- 1 kBTU/h is about 293 W; 100 kBTU/h is around 29.3 kW.
- 1 kcal/h is exactly 1.163 W. A 500 kcal/h workout is 581.5 W.
- 1 ft-lbf/s is about 1.3558 W; 550 of them is 1 mechanical hp.
Common power comparisons
Each row shows the same power in every common unit so you can sanity check a spec sheet against what you have on hand.
| Context | W | kW | hp | PS | BTU/h |
|---|---|---|---|---|---|
| Phone charger, USB device | 5 | 0.01 | 0.01 | 0.01 | 17 |
| Old incandescent bulb | 60 | 0.06 | 0.08 | 0.08 | 205 |
| Laptop charger | 100 | 0.1 | 0.13 | 0.14 | 341 |
| Microwave, small AC unit, 1 hp electric motor input | 750 | 0.75 | 1.01 | 1.02 | 2559 |
| Hair dryer, space heater | 1500 | 1.5 | 2.01 | 2.04 | 5118 |
| Water heater, induction stovetop ring | 3000 | 3 | 4.02 | 4.08 | 10236 |
| Portable generator, EV Level 2 charger | 7500 | 7.5 | 10.06 | 10.2 | 25591 |
| Large home heat pump | 15000 | 15 | 20.12 | 20.39 | 51182 |
| Bus stop fast charger | 50000 | 50 | 67.05 | 67.98 | 170607 |
| EV race car powertrain | 250000 | 250 | 335.26 | 339.91 | 853035 |
Conversion factors used
Every factor flows through the SI base unit, the watt (1 W = 1 J/s). Constants: standard gravity g0 = 9.80665 m/s^2, pound = 0.45359237 kg, foot = 0.3048 m, IT BTU = 1055.05585262 J, IT calorie = 4.1868 J.
- 1 hp (mech) = 550 ft-lbf/s = 745.69987 W
- 1 PS (metric) = 75 kgf-m/s = 735.49875 W
- 1 hp (electric) = 746 W (NEMA, exact)
- 1 hp (boiler) = 9809.5 W (ASME)
- 1 kW = 3412.142 BTU/h
- 1 BTU/h = 0.293071 W
- 1 ton refrigeration = 12,000 BTU/h = 3516.85 W
- 1 kcal/h = 1.163 W exact
- 1 cal/s = 4.1868 W (IT calorie)
- 1 ft-lbf/s = 1.355818 W
Watch which horsepower you mean
Three definitions of horsepower are common and they differ by one to a few percent. Mechanical hp (US auto, 745.7 W) is the most common. Metric horsepower (PS or CV, 735.5 W) shows up on European and Japanese spec sheets. Electric horsepower (746 W) is the NEMA standard for industrial motor name plates. Boiler horsepower (9.81 kW) is a steam rating and is not comparable to engine output. The BTU and kcal units used here are the IT (International Table) values, the same convention HVAC, ISO 31-4, and most reference tables use; thermochemical variants differ by less than 0.1 percent.
How to use
- Type a power value into the input. Comma decimals, dot decimals, scientific notation, thousand separators, and unit suffixes (like 100 kW, 200 hp, 12000 BTU/h, or 1 ton) are all accepted.
- Pick the From unit if it was not auto-detected. The From buttons are grouped into Metric / SI, Horsepower (including PS / CV), Thermal / HVAC (BTU/h, tons, kcal/h), and Other (erg/s).
- Read the headline cards for kW, mechanical hp, metric PS, and BTU/h, then scroll the per-system grids to copy any specific row.
- Use Quick conversions for the top kW to hp, hp to kW, BTU to kW, and 1 ton to kW searches, or Show units to focus on Metric, Imperial / HP, or Thermal / HVAC results only.
- Click Copy on any unit card to grab the value, or Copy summary for the full text-only table to drop into an email, ticket, or doc.
About this tool
Power Converter turns any power reading into every common unit at the same time, so you can pick the one that matches the spec sheet, manual, dashboard, or contract you are working with. Paste a value (digits with comma or dot decimals, scientific notation, thousand separators, and unit suffixes are all accepted) and the parser figures out whether you typed 100 kW, 200 hp, 12000 BTU/h, 1 ton, or 500 kcal/h and normalizes it through the SI base unit, the watt. The output panel covers the cases the catalog did not have together in one place: SI metric (milliwatts, watts, kilowatts, megawatts, gigawatts, and joules per second), every common horsepower (mechanical hp = 745.69987 W = 550 ft-lbf/s, metric horsepower PS or CV = 735.49875 W = 75 kgf-m/s, NEMA electric hp = 746 W exact, and ASME boiler hp = 9809.5 W), the full thermal and HVAC family (BTU per hour, BTU per minute, kBTU/h, tons of refrigeration where 1 ton = 12,000 BTU/h exactly, kilocalories per hour where 1 kcal/h = 1.163 W exact, kilocalories per second, and IT calories per second), foot-pounds per second for legacy mechanical specs, and the CGS erg per second still seen in astrophysics. Quick presets cover the top conversion searches (kW to hp, hp to kW, watts to hp, kW to BTU/h, BTU/h to kW, 1 ton to kW, kW to PS, PS to hp, kcal/h to W) so the answer to the question someone actually typed lands in one click. Headline cards highlight kW, mechanical hp, metric PS, and BTU/h so the four most-cited values are visible without scrolling. A comparison table shows the same wattage across W, kW, hp, PS, and BTU/h for ten real-world readings (a phone charger, an old incandescent bulb, a microwave, a hair dryer, a portable generator, an EV Level 2 charger, a large home heat pump, and a 250 kW race car powertrain) so you can sanity check any number you type. A suffix-aware suggestion bar nudges you if you typed a value with a unit that does not match the selected source unit, so 100 hp is never silently treated as 100 kW. Useful for car spec sheets and engine comparisons (kW vs hp vs PS), HVAC sizing (BTU/h vs kW vs tons), portable generator and inverter shopping, EV charger and home solar planning, gym equipment readouts (kcal/h vs watts), water-heater and boiler ratings, industrial motor name plates, lab and physics homework, and any moment you need to translate a number from one regional convention to another. All parsing, conversion, and formatting run locally on your device using exact NIST conventional constants (standard gravity g0 = 9.80665 m/s^2, pound = 0.45359237 kg, foot = 0.3048 m, IT BTU = 1055.05585262 J, IT calorie = 4.1868 J), so the power readings you paste here, including private engineering data, never leave your browser tab.
Free to use. Works in your browser. No signup, no login.
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