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Miraç Özdemir
Unit Converters

Power Unit Converter: kW, Horsepower (PS, hp), BTU/h

Convert power between watts, kilowatts, megawatts, metric horsepower (PS), mechanical horsepower (hp), BTU per hour and kcal per hour.

Version 2

Things to keep in mind:

  • Metric horsepower (735.5 W) and mechanical horsepower (745.7 W) differ by about 1.4 %; check which definition your source uses. The 746 W "electrical horsepower" used for electric motors is not listed separately.
  • An air conditioner’s BTU/h rating is its cooling/heating capacity; converting it to electricity use needs the unit’s efficiency (EER, COP), which this tool does not cover.
  • Engine power (kW/PS) differs from power measured at the wheels; drivetrain losses are not considered.

Calculator

Value to convert

The power to convert (up to 6 decimals, not negative).

The unit of the value you entered.

The unit for the main result. Equivalents in all common units are listed as well.

After the first calculation, the result updates automatically when you change a value.

Result

Enter the values and press Calculate to see the result here.

About this tool

This tool converts power (energy used or produced per unit of time) between the watt and its multiples, two definitions of horsepower, BTU per hour and kcal per hour, and lists the value in every unit.

Formula: result = value × (watts per source unit) ÷ (watts per target unit)

The factors are derived exactly from their definitions (NIST SP 811):

  • Metric horsepower (PS, CV) = 75 kgf·m/s = 75 × 9.80665 = 735.49875 W. This is the horsepower used on vehicle papers in Turkey and continental Europe.
  • Mechanical horsepower (hp, imperial/US) = 550 ft·lbf/s ≈ 745.69987158 W
  • 1 BTU/h = 1,055.05585262 J ÷ 3,600 s ≈ 0.29307107 W
  • 1 kcal/h = 4,184 J ÷ 3,600 s ≈ 1.16222222 W

Example: 100 hp = 100 × 745.69987158 W ≈ 74.56998716 kW; 1 kW ≈ 1.35962162 PS. A 12,000 BTU/h air conditioner has a cooling capacity of 12,000 × 0.29307107 ≈ 3,516.85 W ≈ 3.52 kW. A car rated 110 kW on its papers is 149.5584 metric PS and 147.51243 hp.

How to read the result The "Result" field is the value in your target unit (8 decimals); the list shows the same power in every unit with 6 decimals. The conversion factor tells how many target units one source unit equals. PS and hp are different definitions, so check which one your source value uses.

An air conditioner’s BTU/h rating is its cooling capacity, not its electricity use; the electrical power drawn is much lower, depending on the efficiency ratio (EER/SEER). Boilers are often rated in kcal/h or kW.

How to use

  1. Enter the power you want to convert.
  2. Select its unit under From unit; for the horsepower on European vehicle papers choose Metric horsepower (PS).
  3. Select the unit you want the result in under To unit.
  4. Select Calculate.

Notes

The main result is rounded half-up (HALF_UP) to 8 decimals, the unit equivalents to 6 and the conversion factor to 10 decimals. The internal base is joules per hour, so every factor is a terminating decimal. BTU is the International Table BTU, the calorie the thermochemical calorie.

Frequently asked questions

4 questions

  1. Metric horsepower (PS) is 0.73549875 kW. Imperial/US mechanical horsepower (hp) is ≈ 0.74569987 kW.

Next step

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