Horsepower to Watts Converter Formula
Understand the math behind the horsepower to watts converter. Each variable explained with a worked example.
Formulas Used
Watts
watts = hp * 745.7Kilowatts
kilowatts = hp * 0.7457BTU per Hour
btu_per_hr = hp * 2544.43Variables
| Variable | Description | Default |
|---|---|---|
hp | Horsepower(hp) | 150 |
How It Works
How to Convert Horsepower to Watts
Formula
Watts = Horsepower × 745.7
Kilowatts = Horsepower × 0.7457
One mechanical horsepower equals 745.7 watts. This is the standard mechanical (or imperial) horsepower defined by James Watt. Note that metric horsepower (PS) is slightly different at 735.5 watts.
Worked Example
Convert 150 horsepower to watts and kilowatts.
- 01Watts = 150 × 745.7 = 111,855 W
- 02Kilowatts = 150 × 0.7457 = 111.855 kW
- 03BTU/hr = 150 × 2544.43 = 381,664.5 BTU/hr
Frequently Asked Questions
What is the difference between HP and PS?
HP (mechanical horsepower) equals 745.7 watts. PS (metric horsepower or Pferdestärke) equals 735.5 watts. PS is used in European vehicle specifications.
How did horsepower originate?
James Watt coined the term in the late 1700s to market his steam engines. He estimated that a draft horse could do 33,000 foot-pounds of work per minute, which became the definition of 1 HP.
How many HP is an electric car motor?
Electric car motors typically range from 100 HP to over 1,000 HP for high-performance models. Since electric motors deliver instant torque, the driving experience differs significantly from combustion engines.
Ready to run the numbers?
Open Horsepower to Watts Converter