Power Conversion Calculator
Convert watts, kilowatts, horsepower, BTU per hour, and all major power units instantly.
Power Unit Converter
Power Unit Conversion Reference Table
Power unit conversion factors referenced to watts (W). Multiply any power value by its factor to get watts, then divide by the target unit factor.
| Unit | Symbol | Factor to Watts (W) |
|---|
IT = International Table | th = Thermochemical. To convert between any two units: (value in A × factor A) ÷ factor B = value in B.
How to Convert Power Units
Power conversion uses a single conversion factor approach: every unit is converted to watts first, then from watts to the target unit. This makes it possible to convert between any two units using a two-step multiplication.
For example, to convert 50 BTU/h (IT) to watts, multiply 50 by 0.2930711 to get approximately 14.65 watts. To go from watts to any other unit, divide instead.
Converting Horsepower to Kilowatts
Power conversion from horsepower to kilowatts is one of the most common requests, especially for vehicle and engine specifications. One mechanical horsepower equals 0.7457 kilowatts. Multiply horsepower by 0.7457 to get kilowatts, or multiply kilowatts by 1.34102 to get mechanical horsepower.
Converting BTU per Hour to Watts
Heating and cooling equipment often uses BTU per hour (BTU/h) while electrical ratings use watts. One BTU/h (International Table) equals 0.29307 watts. Multiply BTU/h by 0.29307 to get watts. To go the other direction, multiply watts by 3.41214 to get BTU/h.
Understanding Power Units
What Is a Watt?
A watt (symbol W) is the SI unit of power, equal to one joule per second. It measures the rate of energy transfer. Watts are used universally for electrical devices, from small household appliances to large industrial generators. The unit is named after Scottish engineer James Watt.
What Is Horsepower?
Horsepower (hp) is a unit of power originally defined by James Watt to compare the output of steam engines with the power of draft horses. There are several variants: mechanical horsepower (745.7 W) is standard in the United States, metric horsepower or PS (735.499 W) is common in Europe, electric horsepower (746 W) is used for electric motors, and boiler horsepower (9809.5 W) is used for steam boilers.
What Is a BTU per Hour?
BTU stands for British Thermal Unit, a measure of heat energy. BTU per hour (BTU/h) measures the rate of heat transfer and is widely used in the heating, ventilation, and air conditioning (HVAC) industry. Air conditioners and heaters in the United States are often rated in BTU per hour.
Watt vs Kilowatt
A kilowatt (kW) equals exactly 1,000 watts. Kilowatts are used to rate larger equipment such as home appliances, electric vehicle motors, and solar panels. Electric utility bills use kilowatt-hours (kWh), which measure energy consumption rather than instantaneous power.
Power Conversion Formulas
Horsepower to Watts
Kilowatts to Horsepower
BTU per Hour to Watts
Watts to BTU per Hour
Frequently Asked Questions
One mechanical horsepower equals exactly 745.7 watts. One electric horsepower equals 746 watts, and one metric horsepower equals 735.499 watts.
To convert kilowatts to mechanical horsepower, multiply by 1.34102. For example, 10 kilowatts times 1.34102 equals 13.41 horsepower.
One kilowatt equals exactly 1,000 watts. To convert kilowatts to watts, multiply by 1,000. To convert watts to kilowatts, divide by 1,000.
Watts measure power in the SI system, while BTU per hour is a unit of heat flow rate used in heating and cooling systems. One watt equals approximately 3.41214 BTU per hour.
Horsepower is used primarily to rate engines in vehicles, electric motors, and industrial machinery. Mechanical horsepower (hp) is standard in the United States, while metric horsepower (PS) is used in Europe.
The most efficient method is to convert any unit to watts first using its conversion factor, then convert from watts to your target unit. This two-step approach works for all power unit combinations without needing individual conversion tables for every pair.