DIY Cost Tools
Power Converter
CONVERSION CALCULATOR
Convert power between watts, kilowatts, megawatts, mechanical or metric horsepower, BTU per hour, and foot-pounds per second.
How it works
The converter expresses every source value in watts and then divides by the watt factor of the destination unit.
Conversion formula
Converted power = entered power × watts per source unit ÷ watts per destination unit.
Worked example
5 mechanical horsepower is approximately 3.7285 kilowatts.
Important limits
- Mechanical horsepower and metric horsepower are different.
- Rated input power and useful output power differ when equipment is not 100% efficient.
- BTU per hour is a power rate, while BTU alone is energy.
Frequently asked questions
How many watts are in horsepower?
One mechanical horsepower is approximately 745.699872 watts.
Is kW a unit of energy?
No. Kilowatt is power. Kilowatt-hour is energy.
Power is not energy
Power measures the rate at which energy is used or produced. Watts, kilowatts, horsepower, and BTU per hour can describe power, while kilowatt-hours and joules describe energy. To estimate energy use, multiply power by operating time and account for the correct unit conversion.
Nameplate power may differ from actual input or output under real operating conditions. Motor efficiency, power factor, load, temperature, and startup demand can affect electrical calculations. Mechanical and electrical horsepower conversions also use defined factors that may not capture system losses. Use full precision for engineering work and consult equipment documentation when sizing circuits, generators, inverters, or HVAC components; a simple unit conversion does not replace code or manufacturer requirements.
Review notes
Mechanical horsepower and metric horsepower use their standard watt equivalents. Last reviewed September 30, 2026.