Power Unit Converter
Convert watts, kilowatts, horsepower, BTU per hour, kilocalories per hour and refrigeration tons online
What is power unit conversion?
Power is the rate at which energy is converted or work is done. The same value may be written as watts on an appliance label, kilowatts on a motor nameplate, horsepower in a car brochure, or BTU/h in an air-conditioning specification. This converter uses the watt as the common reference point, so it can move cleanly between electrical, mechanical and HVAC units. It is useful for checking whether a 0.75 kW motor is roughly a 1 hp motor, comparing hp with PS, or translating a 12000 BTU/h air conditioner into kW. The calculation runs in the browser and does not upload the number you enter.
How to use
Steps
- Enter the power value, for example 1500 or 0.75.
- Choose the source unit and the target unit.
- Click Convert to open a result page with the value and formula.
- Use the related conversions when you want the same number in other units.
Before you convert
- Use W, kW and MW for electrical and industrial loads; use hp or PS only when the source document does.
- Mechanical horsepower and metric horsepower are close but not identical: 1 hp ≈ 745.7 W, while 1 PS = 735.49875 W.
- For cooling capacity, 1 refrigeration ton is defined here as 12000 BTU/h, or about 3.51685 kW.
Use cases
Technical principle
Power is the rate of energy conversion, transfer or work over time, usually written as P. The SI derived unit is the watt, where 1 W = 1 J/s. For the units in this tool, every conversion is linear: multiply the input by the source unit factor to get watts, then divide by the target unit factor. Electrical units use decimal SI prefixes. 1 mW is 0.001 W, 1 kW is 1000 W, 1 MW is 1,000,000 W, and 1 GW is 1,000,000,000 W. Mechanical horsepower follows the imperial definition 1 hp = 550 ft·lbf/s ≈ 745.699871582 W. Metric horsepower, often written PS, is 75 kgf·m/s = 735.49875 W. Because these two horsepower standards are not equal, they should be kept separate when comparing engines, pumps or compressors. Thermal and HVAC units are converted through heat per unit time. BTU/h means British thermal units per hour; here it uses the common International Steam Table BTU, so 1 BTU/h ≈ 0.293071 W. Kilocalories per hour are common in heat-load estimates, with 1 kcal/h ≈ 1.162222 W. A refrigeration ton is defined as 12000 BTU/h, so 1 RT ≈ 3516.852842 W. It describes cooling rate, not physical weight. JavaScript double-precision numbers are sufficient for this range of units. The display is rounded to a practical number of significant digits because real nameplate and HVAC values rarely justify long decimal tails.
- Every conversion goes through watts as the base unit.
- SI prefix units use powers of ten, so W, kW, MW, GW and mW are straightforward.
- Mechanical hp and metric PS are different standards.
- BTU/h, kcal/h and refrigeration tons express heat transfer per unit time.
- 1 refrigeration ton = 12000 BTU/h ≈ 3.51685 kW.
- Displayed values are rounded to avoid false precision.
Examples
Appliance load
1500 W = 1.5 kW ≈ 5118.2 BTU/hCar engine output
200 hp ≈ 149.14 kW ≈ 202.77 PSAir-conditioning capacity
1 RT = 12000 BTU/h ≈ 3.5169 kWData centre load
2 MW = 2000 kW = 2,000,000 WThermal load
860 kcal/h ≈ 1 kWMechanical power
550 ft·lbf/s = 1 hp ≈ 745.7 WFAQ
Which units are supported?
Watts, kilowatts, megawatts, gigawatts, milliwatts, mechanical horsepower, metric horsepower, BTU per hour, kilocalories per hour, foot-pounds-force per second and tons of refrigeration. The set covers common electrical, mechanical, thermal and cooling-capacity documents.
How many horsepower are in 1 kW?
1 kW is about 1.3410 mechanical horsepower, or about 1.3596 metric horsepower. The difference is small but real, so car and pump specifications should not mix hp and PS without checking the standard.
How do BTU/h and kW convert?
1 BTU/h is about 0.293071 W, so 3412.142 BTU/h is about 1 kW. Common HVAC ratings such as 9000, 12000 and 24000 BTU/h are about 2.64, 3.52 and 7.03 kW.
Is a refrigeration ton a weight?
No. It is a cooling-capacity unit. This tool uses the common engineering definition: 1 refrigeration ton = 12000 BTU/h ≈ 3.51685 kW.
What is the difference between power and energy?
Power is a rate; energy is an amount. W, kW and hp are power units. J, kWh and kcal are energy units. A 1 kW device running for one hour uses 1 kWh of energy.
Why are results rounded?
Most nameplate values and engineering estimates only have a few meaningful digits. The converter calculates with double precision but rounds the display so the result does not imply unrealistic accuracy.
Can I convert negative power?
The UI is aimed at ratings, loads and cooling capacity, so it expects non-negative values. In engineering models, a negative sign may describe direction, generation or absorption, but the unit factors are unchanged.