A power converter for engines, motors and air conditioners
This power converter translates between watts and kilowatts, the three kinds of horsepower (mechanical hp, metric PS and electrical hp), BTU per hour, tons of refrigeration, kilocalories per hour and foot-pounds per second. Enter a rating and every equivalent appears at once, with the factor used.
It is useful when a car brochure quotes PS but a review uses kW, when a water pump is sold in “HP” and your inverter is rated in watts, when comparing a 1.5-ton air conditioner with a heater rated in BTU/h, or when a generator spec sheet mixes kW and horsepower. Each horsepower variant is labelled, because they differ by up to 1.4%.
How to use the Power Converter
- Type the power rating in the Value box — for example 1.5 for a 1.5-ton AC or 150 for a 150 PS engine.
- Pick its unit under From. Search “hp”, “PS”, “BTU” or “ton”.
- Pick the unit you want under To, or use the round swap button.
- Read the result and the formula; set Precision and press Copy if you need the number elsewhere.
- Look at the list of every power unit to compare all horsepower types and heating units together, or tap a quick conversion such as “1 TR → kW”.
Power Converter features
Three horsepowers, clearly named
Mechanical (550 ft·lbf/s), metric PS (75 kgf·m/s) and electrical (746 W) are separate units, not one vague “hp”.
AC tonnage
Tons of refrigeration convert to BTU/h and kW, so a “1.5 ton” split AC can be compared with any other cooling rating.
Heating units
BTU per hour and kcal per hour for boilers, geysers, heaters and furnaces.
From milliwatts to gigawatts
Laser pointers, phone chargers, homes, power stations — all in one list.
Exact definitions
Every factor is built from the exact foot, pound, standard gravity and International Table BTU.
Power conversion factors
A watt is one joule of energy per second. James Watt defined the horsepower in the 18th century as 33,000 foot-pounds of work per minute (550 per second) to sell his steam engines against working horses. Continental Europe later adopted a rounder metric version — 75 kilogram-force metres per second — called Pferdestärke (PS), cheval-vapeur (CV) or paardenkracht (pk).
| Unit | Value in watts | Notes |
|---|---|---|
| Horsepower, mechanical (hp) | ≈ 745.69987 | 550 ft·lbf/s; also used for bhp |
| Metric horsepower (PS) | 735.49875 (exact) | 75 kgf·m/s; car specs in Europe and India |
| Horsepower, electrical (hp(E)) | 746 (exact) | Motor and pump ratings |
| BTU per hour (BTU/h) | ≈ 0.2930711 | US heating and cooling |
| Ton of refrigeration (TR) | ≈ 3,516.853 | 12,000 BTU/h — AC tonnage |
| Kilocalorie per hour (kcal/h) | ≈ 1.162222 | Heating, older European specs |
| Foot-pound force per second | ≈ 1.3558179 | Mechanical engineering |
| Kilowatt (kW) | 1,000 | Engines, appliances, solar systems |
| Megawatt (MW) | 1,000,000 | Wind turbines, power plants |
Worked examples
kW to hp — divide by 0.7457. A 100 kW car engine makes 134.1 mechanical hp, or 136 PS (divide by 0.73549875).
PS to kW — multiply by 0.73549875. A 150 PS engine is 110.3 kW.
AC tons to kW — multiply by 3.51685. A 1.5-ton air conditioner removes 18,000 BTU/h of heat, which is 5.28 kW of cooling. The electricity it draws is far less: at an efficiency ratio of 3.5, it needs about 5.28 ÷ 3.5 = 1.5 kW of electrical power.
Pump HP to kW — multiply by 0.746. A 5 HP water pump motor is rated at 3.73 kW of output.
Watts to BTU/h — multiply by 3.41214. A 1,500 W space heater gives out 5,118 BTU/h of heat.
kW vs kWh
Power (kW) is how fast energy is used; energy (kWh) is how much is used in total. A 2 kW heater running for 3 hours uses 6 kWh. Electricity bills charge for kWh, so to estimate running costs multiply the power by the hours of use and then use the electricity bill calculator. For converting amounts of energy — joules, kWh, BTU, calories — switch to the energy converter.
Common power conversions
| From | To |
|---|---|
| 1 hp | 0.7456998716 kW |
| 1 kW | 1.34102209 hp |
| 1 PS | 0.73549875 kW |
| 1 PS | 0.9863200706 hp |
| 1 hp(E) | 0.746 kW |
| 1 kW | 3,412.141633 BTU/h |
| 1 W | 3.412141633 BTU/h |
| 12,000 BTU/h | 3.516852842 kW |
| 1 TR | 3.516852842 kW |
| 1.5 TR | 5.275279263 kW |
| 1 kW | 860.4206501 kcal/h |
| 1 hp | 550 ft·lbf/s |
Tips
- bhp vs hp. Brake horsepower is mechanical horsepower measured at the engine’s output shaft; the unit itself is the same 745.7 W.
- Check which horsepower a brochure means. Indian and European car makers usually quote PS (about 1.4% smaller than hp), while US makers quote hp.
- Cooling capacity is not electricity use. AC tonnage and BTU/h describe heat removed; the power drawn from the socket is lower and depends on the efficiency rating.
Power Converter FAQ
How do I convert kW to hp?
Divide kilowatts by 0.7457 (or multiply by about 1.341) for mechanical horsepower. For metric horsepower (PS), divide by 0.73549875.
How many watts is 1 horsepower?
Mechanical horsepower is about 745.7 W, metric horsepower (PS) is 735.49875 W, and electrical horsepower is exactly 746 W. The power converter lists all three.
What is the difference between hp and PS?
Both measure engine power, but PS (metric horsepower) is defined as 75 kgf·m/s = 735.5 W, while mechanical hp is 550 ft·lbf/s = 745.7 W. One PS is about 0.986 hp.
How many kW is a 1.5-ton AC?
A 1.5-ton air conditioner provides 18,000 BTU/h, or about 5.28 kW, of cooling. Its electrical consumption is lower, typically between 1 and 2 kW depending on its efficiency.
How many BTU/h is 1 kW?
One kilowatt is about 3,412 BTU/h, and 1 BTU/h is about 0.293 W.
Why is it called a ton of refrigeration?
It is the cooling power needed to melt one short ton (2,000 lb) of ice in 24 hours: 288,000 BTU per day, or 12,000 BTU per hour.