Watt Converter
Convert between watts, kilowatts, megawatts, horsepower, BTU/h, and 14 other power units. Free online watt converter with charts and detailed unit breakdown.
About This Calculator
The Watt Converter is a comprehensive power unit conversion tool that lets you convert between 14 different power units including watts (W), kilowatts (kW), megawatts (MW), gigawatts (GW), terawatts (TW), milliwatts (mW), mechanical horsepower (hp), electric horsepower, metric horsepower, BTU per hour, foot-pounds per second, calories per second, ergs per second, and joules per second.
A watt (W) is the SI unit of power, defined as one joule per second (1 W = 1 J/s). It measures the rate at which energy is transferred or converted. Power conversion is essential across many fields including electrical engineering, mechanical engineering, physics, HVAC, automotive engineering, and energy production.
The converter works by first converting your input value to a baseline in watts using the standard conversion factor for the source unit, then converting from watts to the target unit. For example, to convert 10 horsepower to kilowatts: 10 hp × 745.7 = 7457 W, then 7457 / 1000 = 7.457 kW.
Power Unit Reference
Milliwatt (mW): 1 mW = 0.001 W. Used for low-power electronics, laser pointers, and audio equipment.
Watt (W): The base SI unit. Used for everyday appliances like light bulbs (5-100 W) and microwave ovens (600-1200 W).
Kilowatt (kW): 1 kW = 1000 W. Used for larger appliances, electric vehicle charging (50-350 kW), and solar panel arrays.
Megawatt (MW): 1 MW = 10⁶ W. Used for power plant output, wind turbines (2-8 MW), and data center power capacity.
Gigawatt (GW): 1 GW = 10⁹ W. Used for large power stations and national grid capacity.
Horsepower (hp): Three common definitions exist. Mechanical hp (745.7 W) is used in the US for engines. Metric hp (735.5 W) is used in Europe. Electric hp (746 W) is used for electric motors.
Regional Notes
India: Power is commonly expressed in watts, kilowatts, and horsepower. Electricity bills use kilowatt-hours (kWh). The Indian power grid has a capacity of approximately 400 GW.
United States: Horsepower (mechanical) is widely used for vehicle engines and motors. BTU/h is common in HVAC for heating/cooling capacity. Home electricity is billed in kWh.
United Kingdom: Both kilowatts and horsepower are used. Vehicle tax is based on CO₂ emissions rather than power, but horsepower remains common in automotive advertising.
Frequently Asked Questions
How do I convert watts to kilowatts?
To convert watts to kilowatts, divide the power value by 1000. For example, 1500 W / 1000 = 1.5 kW.
How many watts are in one horsepower?
One mechanical horsepower equals approximately 745.7 watts. One metric horsepower equals 735.5 watts, and one electric horsepower equals 746 watts.
How do I convert BTU per hour to watts?
To convert BTU/h to watts, multiply the BTU/h value by 0.293071. For example, 1000 BTU/h × 0.293071 = 293.07 W.
What is the difference between a watt and a watt-hour?
A watt (W) is a unit of power measuring the rate of energy transfer, while a watt-hour (Wh) is a unit of energy measuring the total energy consumed over time. One watt-hour equals 3600 joules.
What is a gigawatt and how big is it?
A gigawatt (GW) equals one billion watts (10⁹ W). It is typically used to measure the output of large power plants. For context, a typical nuclear power plant produces about 1 GW of electricity.
How do I convert watts to joules per second?
Watts and joules per second are actually the same unit. By definition, 1 watt equals 1 joule per second (1 W = 1 J/s). So no conversion is needed.
How many watts does a typical household appliance use?
Common household appliances range from 5 W (LED bulb) to 3500 W (clothes dryer). A refrigerator uses 100-800 W, a microwave uses 600-1200 W, and a washing machine uses 500-1000 W.
Is this watt converter free to use?
Yes, this watt converter is completely free to use with no registration or hidden charges. It supports 14 different power units including W, kW, MW, GW, TW, hp, and BTU/h.