Available Power units

• watt conversions

  The watt is the SI base unit of power. It is universally used to measure the rate of energy consumption or production in electrical appliances, engines, lighting, and virtually all power-related specifications.

• kilowatt conversions

  A kilowatt is a unit of power equal to 1,000 watts. It is commonly used to rate electric motors, heating systems, solar panels, EV chargers, and industrial equipment.

• horsepower (mechanical) conversions

  Mechanical horsepower is a traditional unit of power equal to approximately 745.7 watts. It is widely used in automotive and industrial contexts to express engine output, pump capacity, and motor ratings.

• megawatt conversions

  A megawatt is a unit of power equal to one million watts. It is used to rate the output of power plants, large industrial facilities, and grid-scale renewable energy installations.

• gigawatt conversions

  A gigawatt is a unit of power equal to one billion watts. It is used to express the total power output of national electricity grids, large power stations, and national energy policy targets.

• milliwatt conversions

  A milliwatt is a unit of power equal to one thousandth of a watt. It is used in low-power electronics, wireless communication systems, laser specifications, and medical device power ratings.

• microwatt conversions

  A microwatt is a unit of power equal to one millionth of a watt. It is used in ultra-low-power electronics, energy harvesting systems, biosensors, and precision scientific instrumentation.

• BTU per hour conversions

  BTU per hour is a unit of power used to measure the heating or cooling capacity of HVAC equipment. It is the standard rating system for air conditioners, furnaces, and heat pumps in the United States.

• kilocalorie per hour conversions

  Kilocalorie per hour is a unit of power expressing energy transfer as dietary calories per hour. It is used in nutrition and exercise physiology to express the rate of energy expenditure during physical activity.

• ton of refrigeration conversions

  A ton of refrigeration is a power unit measuring the heat removal capacity of cooling systems, equal to 12,000 BTU per hour. It is the standard capacity rating for commercial and industrial air conditioning units in the United States.

Assumption: horsepower values use mechanical horsepower.

Full Power conversion matrix

About Power

Units of power

Real-world uses

Power units quantify the rate of energy transfer in contexts from household appliances to power plants. Light bulbs are rated in watts, air conditioners in BTU/h or kilowatts, and car engines in horsepower or kilowatts. Utility-scale solar farms are measured in megawatts, while data centres track their energy efficiency in kilowatt measurements. Athletes measure peak output in watts on cycling ergometers.

History

James Watt coined the term "horsepower" in the late 1700s to market his improved steam engine, estimating that a brewery horse could sustain 33,000 foot-pounds of work per minute. The watt was named in his honour and adopted as the SI unit of power in 1960. Before standardisation, various "horsepower" definitions proliferated — metric, electrical, boiler, and water horsepower — each differing slightly.

Common mistakes

Many people confuse watts (power) with watt-hours (energy): a 100 W bulb running for 10 hours uses 1,000 Wh, or 1 kWh. Another mistake is assuming metric horsepower and mechanical horsepower are equal — metric HP is 735.5 W while mechanical HP is 745.7 W, a difference of about 1.4%. People also erroneously compare peak and sustained power ratings, which can differ dramatically for motors and engines.

Measurement standards

The watt is the SI derived unit of power, defined as one joule per second (kg·m²/s³). Horsepower remains in widespread informal use, particularly in the automotive industry, but has no single universal definition across regions.

Did you know?

The human body at rest produces about 80 watts of power — roughly enough to keep an incandescent light bulb glowing. During intense exercise, a trained cyclist can sustain over 400 watts, and elite sprinters briefly exceed 2,000 watts.

Common values