Power

About Power Conversion

Power measures the rate at which energy is transferred, converted, or used per unit time. It's essential for understanding electrical appliances, vehicle performance, heating/cooling systems, industrial machinery, and renewable energy systems. Whenever you see a rating in watts or horsepower, you're looking at power.

The SI unit is the watt (W), equal to one joule per second. However, horsepower (hp) remains widely used for engines and motors, while BTU/hour is the standard for heating and cooling capacity in the US. Different regions use different horsepower definitions—mechanical horsepower in the US/UK versus metric horsepower in Europe and Asia.

Our power converter handles all common units for both technical and everyday applications, from comparing car engines to sizing air conditioners and understanding your electricity usage.

Common Power Conversions

Power Unit Reference

Watt (W) – The SI unit of power, equal to 1 joule per second or 1 volt-ampere. Named after James Watt. Used universally for electrical and mechanical power ratings from milliwatts in electronics to gigawatts in power plants.

Kilowatt (kW) – 1,000 watts. The practical unit for household appliances, electric vehicles, and industrial equipment. A typical electric car has a 50-100 kW motor; a home might have 5-10 kW peak demand.

Megawatt (MW) – 1 million watts. Used for power plants, large industrial facilities, and grid capacity planning. A large wind turbine produces 2-5 MW; a nuclear reactor produces 500-1,500 MW.

Mechanical Horsepower (hp) – Defined by James Watt as 550 ft·lbf/s = 745.7 W. Standard in the US and UK for engines, motors, and machinery. A car engine might range from 100-700 hp.

Metric Horsepower (PS/CV/pk) – 735.5 W, slightly less than mechanical hp. Used in Europe and Asia for vehicle engines. PS (Pferdestärke), CV (Cavallo Vapore), and pk (paardenkracht) all mean the same thing.

BTU/hour (BTU/h) – Used for heating and cooling capacity in the US. 1 BTU/h = 0.293 W. Air conditioners and furnaces are commonly rated in BTU/h or thousands of BTU/h (MBH).

Ton of Refrigeration – HVAC unit for cooling capacity. 1 ton = 12,000 BTU/h = 3.517 kW. Represents the cooling power needed to freeze one short ton (2,000 lb) of ice in 24 hours.

Learn More

Explore our in-depth guides on this topic:

• How to Convert Kilowatts to Horsepower
• Watts vs Horsepower: Understanding Power Units
• Appliance Power Consumption Guide