Power Converter

Convert between watts, kilowatts, horsepower, BTU per hour, calories per second, joules per second, and other power units with scientific precision.

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Power Units Explained

Watt (W)

The SI unit of power, defined as one joule of energy transferred per second. 1 W = 1 J/s = 1 kg·m²/s³. The foundation of electrical and mechanical power measurements.

Common uses: Electrical appliances, light bulbs, mechanical power, solar panels, computing devices.

Kilowatt (kW)

A unit of power equal to 1,000 watts. 1 kW = 1,000 W ≈ 1.34 hp. Widely used for household electricity consumption and industrial machinery.

Common uses: Electricity billing, home appliances, electric vehicles, industrial equipment ratings.

Horsepower (hp)

An imperial unit of power, originally defined as the power of a horse. 1 hp ≈ 746 W = 0.746 kW. Still used extensively in automotive and mechanical engineering.

Variants: Mechanical (550 ft·lbf/s), Metric (75 kgf·m/s), Electric, Water, and Boiler horsepower have slightly different values.

BTU (British Thermal Unit) per Hour

A unit of power expressing the rate of heat energy transfer. 1 BTU/h ≈ 0.293 W. Commonly used in HVAC systems and air conditioning specifications.

Common uses: Air conditioning capacity, heating systems, thermal power, climate control equipment ratings.

Joule per Second (J/s)

Equivalent to the watt. Expresses power as energy per unit time. 1 J/s = 1 W. Fundamental SI-derived unit for power.

Common uses: Scientific calculations, energy physics, power analysis, thermodynamics.

Calorie per Second

A unit of power based on calories (units of heat energy). 1 cal/s ≈ 4.184 W. Used in nutritional energy (food calories are kilocalories) and thermal physics.

Note: Food/dietary "Calories" are actually kilocalories, equal to ~4,184 watts per second when consumed over time.

Megawatt (MW)

A unit of power equal to one million watts. 1 MW = 1,000,000 W ≈ 1,341 hp. Used for large power stations and industrial facilities.

Common uses: Power plant capacity, wind turbine ratings, large hydroelectric facilities, city-scale power generation.

Power Reference Values

  • Human body (at rest): ~100 watts
  • Typical household bulb (LED): ~10 watts
  • Household microwave: ~1,000 watts (1 kW)
  • Electric vehicle (charging): ~7-22 kW
  • Car engine: ~100-300 horsepower (75-225 kW)
  • Large wind turbine: ~2-5 MW
  • Nuclear power plant: ~1,000 MW (1 GW)
  • World average household consumption: ~1.5-3 kW continuous average

SI Power Prefixes

Large units: Kilowatt (kW), Megawatt (MW), Gigawatt (GW), Terawatt (TW), Petawatt (PW), Exawatt (EW)

Small units: Milliwatt (mW), Microwatt (µW), Nanowatt (nW), Picowatt (pW), Femtowatt (fW), Attowatt (aW)

Each step represents a factor of 1,000 difference in power magnitude.