Conversion Formula
Multiply horsepower by 0.7457 to get kilowatts — the unit used in EV specifications, European vehicle registration and all electrical work.
Complete Guide to Horsepower to Kilowatts Conversion
What is a Horsepower?
Horsepower (hp) is a legacy unit devised to compare steam engines with draught horses. Mechanical horsepower equals 745.7 watts; the metric variant (PS) equals 735.5 watts.
What is a Kilowatts?
The kilowatt (kW) is 1,000 watts, the SI measure of power. It rates electric motors, EV drivetrains, heat pumps, chargers and every piece of electrical equipment.
How the Conversion Works
James Watt estimated that a working horse could lift 550 foot-pounds per second, which equals 745.7 watts. Converting therefore means multiplying or dividing by 0.7457 — or 0.7355 if the source uses metric PS rather than mechanical horsepower.
Why This Conversion Matters
The transition to electric drivetrains has forced two power vocabularies into the same conversation. Buyers compare a 150 hp petrol car against a 110 kW electric one without realising they are the same figure. This conversion makes those comparisons honest.
Scientific Context
Power output alone does not describe drivability. Electric motors deliver peak torque from zero rpm, so an EV with the same kilowatt rating as a combustion engine will typically accelerate faster at low speed despite identical nameplate power.
Step-by-Step Conversion Guide
Follow these steps to convert horsepower to kilowatts manually:
Start with your value in horsepower
Example: You want to convert 10 hp
Apply the conversion formula
Use the formula: kW = hp × 0.7457
Calculate the result
10 hp = 7.457 kW
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Multiply horsepower by 0.7457 to get kilowatts — the unit used in EV specifications, European vehicle registration and all electrical work.
Common Conversions
| Horsepower (hp) | Kilowatts (kW) | Kilowatts → Horsepower |
|---|---|---|
| 1 | 0.7457 | 1 kW = 1.341 hp |
| 5 | 3.7285 | 5 kW = 6.7051 hp |
| 10 | 7.457 | 10 kW = 13.4102 hp |
| 50 | 37.285 | 50 kW = 67.0511 hp |
| 100 | 74.57 | 100 kW = 134.1022 hp |
| 150 | 111.855 | 150 kW = 201.1533 hp |
| 200 | 149.14 | 200 kW = 268.2044 hp |
| 300 | 223.71 | 300 kW = 402.3066 hp |
| 400 | 298.28 | 400 kW = 536.4087 hp |
| 500 | 372.85 | 500 kW = 670.5109 hp |
| 700 | 521.99 | 700 kW = 938.7153 hp |
When You'll Need This Conversion
Comparing EVs and combustion cars
Translate kW motor ratings into the horsepower figures most buyers know.
Industrial motor specification
US motor catalogues list horsepower; European ones list kilowatts.
Pumps and machinery sizing
Match a replacement motor across measurement systems.
Physics of power
Understand how a historical unit maps onto the SI watt.
Pro Tips for Accurate Conversions
kW × 1.34 = hp
A fast mental shortcut accurate to within a fraction of a percent.
Check whether the spec is hp or PS
German and French listings usually mean PS, which reads about 1.4% higher.
Compare continuous, not peak
For workloads like towing, sustained power matters more than headline figures.
Common Mistakes to Avoid
Treating hp and PS as identical
They differ by 1.4%, which shows up in marketing comparisons.
hp = W ÷ 745.7; PS = W ÷ 735.5.
Confusing motor power with battery capacity
A 150 kW motor and a 77 kWh battery describe completely different things.
kW is the rate of work; kWh is the stored energy.
Assuming higher kW means higher consumption
Energy use depends on how the power is used, not the peak rating.
Compare kWh per 100 km for real efficiency.
History & Background
James Watt created horsepower in the 1780s as a marketing device to sell steam engines to mine owners who thought in horses. The unit named after him eventually replaced it.
Key Milestones
Watt defines horsepower as 33,000 foot-pounds per minute.
The watt is adopted as the international unit of power.
Europe standardises vehicle power ratings in kilowatts for registration.
EV launches bring kilowatt drivetrain ratings to mainstream car buyers.
Global Usage Today
Kilowatts are the legal unit for vehicle power across the EU; horsepower dominates US marketing, and PS is standard in German-language markets.
Frequently Asked Questions
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Last verified: April 2026. All conversion factors are based on internationally defined standards.