Quick Answer: Horsepower to Kilowatts
One horsepower is approximately 0.7457 kilowatts (1 hp ≈ 0.7457 kW).
Conversely, 1 kW ≈ 1.341 hp.
Formula: kW = hp × 0.745699872
Worked examples
- 1 hp ≈ 0.7457 kW
- 5 hp ≈ 3.728 kW
- 10 hp ≈ 7.457 kW
Method and limitations
Multiply mechanical horsepower by 0.745699872 to get kW. If the source figure is metric horsepower (PS, CV, ch, pk), multiply by 0.73549875 instead — using the wrong one gives a 1.4% error. Calculations use full-precision constants; answers in this box are rounded for readability (≈ marks a rounded value) and the calculator shows up to 9 significant figures. hp here is mechanical horsepower (745.699872 W). Metric horsepower (PS, CV) is a different unit of 735.49875 W, about 1.4% smaller.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
Multiply mechanical horsepower by 0.745699872 to get kW. If the source figure is metric horsepower (PS, CV, ch, pk), multiply by 0.73549875 instead — using the wrong one gives a 1.4% error.
Moving legacy horsepower specs to kW
Older engine, pump and motor documents often give power in horsepower. Before converting, check which one: mechanical hp (× 0.745699872) or metric PS (× 0.73549875). Applying the wrong factor shifts the result by about 1.4 %.
A rated motor output is mechanical shaft power. Its electrical input is higher by the motor's efficiency, and energy used is power × running time — use the home energy audit calculator with the measured or rated input power for running cost.
Constants and their sources are listed on the methodology page.
Complete Guide to Horsepower to Kilowatts Conversion
What is a horsepower?
Horsepower is a legacy power unit. Mechanical horsepower is 745.699872 W; metric horsepower (PS) is 735.49875 W. Older engine, pump and motor specifications often use one of them.
What is a kilowatt?
The kilowatt (kW) is the SI unit of power used in current motor standards, EU vehicle documents and electrical work.
How the Conversion Works
kW = hp × 0.745699872 for mechanical horsepower, or PS × 0.73549875 for metric horsepower.
Why This Conversion Matters
Moving legacy specifications into SI units is common when replacing equipment or comparing documents from different decades or markets.
Scientific Context
Mechanical horsepower derives from 33,000 ft·lbf per minute; metric horsepower from 75 kgf·m per second. They were defined independently, which is why they differ.
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 × 0.745699872
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 hp by 3 and divide by 4: 200 hp → 150 kW (exact: 149.14). For PS, multiply by 0.7355.
Common Conversions
| Horsepower (hp) | Kilowatts (kW) | Kilowatts → Horsepower |
|---|---|---|
| 1 hp | 0.7457 | 1 kW = 1.34102 hp |
| 5 hp | 3.7285 | 5 kW = 6.70511 hp |
| 10 hp | 7.457 | 10 kW = 13.4102 hp |
| 50 hp | 37.285 | 50 kW = 67.0511 hp |
| 100 hp | 74.57 | 100 kW = 134.102 hp |
| 150 hp | 111.855 | 150 kW = 201.153 hp |
| 200 hp | 149.14 | 200 kW = 268.204 hp |
| 300 hp | 223.71 | 300 kW = 402.307 hp |
| 400 hp | 298.28 | 400 kW = 536.409 hp |
| 500 hp | 372.85 | 500 kW = 670.511 hp |
| 700 hp | 521.99 | 700 kW = 938.715 hp |
When You'll Need This Conversion
Replacing an old motor
Convert a legacy hp nameplate into the kW rating used by current IEC motor catalogues.
Older vehicle documents
Express a horsepower figure from a manual or advert as the kW figure used on EU registration documents.
Pumps and compressors
Bring hp-rated equipment into SI-based energy calculations.
Pro Tips for Accurate Conversions
Identify the horsepower first
Mechanical hp and metric PS are both called "horsepower".
Shaft power is not electrical input
A motor's rated output is mechanical; its electrical input is higher by its efficiency.
Common Mistakes to Avoid
Using 0.7457 for a PS figure
That overstates kW by about 1.4%.
Use 0.73549875 for PS.
Treating motor output as electricity used
Rated output is mechanical power delivered at the shaft.
Electrical input = output ÷ motor efficiency (from the datasheet).
Frequently Asked Questions
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Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.