The mechanical horsepower
Mechanical (imperial) horsepower is defined as exactly 550 ft·lbf/s, or approximately 745.7 W. It is the standard 'horsepower' in the US and is the unit most often quoted for American cars and motorcycles.
Mechanical horsepower to Watts Converter
1 hp = 745.7 W (mechanical horsepower → watt)
1 hp = 745.7 W
1 mechanical horsepower equals 745.7 watts. To convert mechanical horsepower to watts, multiply the mechanical horsepower value by 745.7. For quick reference: 1 hp = 745.7 W, 5 hp = 3728.5 W, 10 hp = 7457 W, 100 hp = 74570 W.
Formula
Watts = Mechanical horsepower × 745.7Quick
When to use mechanical horsepower → watts
Mechanical horsepower to watts multiplies by 745.69987158227 (1 hp = 550 ft·lbf/s exactly, the original Watt definition). A 5 hp compressor motor is 3728.5 W; a 1 hp pool pump is 745.7 W. Use this when a US-rated motor or pump must be matched to a circuit, inverter, or generator sized in watts. The trap is nameplate optimism: consumer tools often quote peak horsepower the motor cannot sustain, so size electrical supply from the continuous watt figure, not the marketing hp.
Boat-engine dealers convert this for buyers comparing an outboard against its electric-shore-power equivalent: a 9.9 hp outboard motor is rated at 7,382 W, the number a marina electrician actually needs when sizing a shore-power charging circuit for an equivalent electric trolling setup, since dock wiring is specified in watts and amps, not horsepower.
How to convert mechanical horsepower to watts
Take your value
Start with your value in mechanical horsepower.
Multiply by 745.7
Multiply the mechanical horsepower value by 745.7. This is the exact conversion factor from mechanical horsepower to watts.
Read the result
The product is your value in watts. For example, 5 hp × 745.7 = 3728.5 W.
Conversion formula
The exact factor from mechanical horsepower to watts is 745.7.
Watts = Mechanical horsepower × 745.7
Mechanical horsepower to Watts conversion table
Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.
| Mechanical horsepower (hp) | Watts (W) |
|---|---|
| 0.1 hp | 74.57 W |
| 0.5 hp | 372.85 W |
| 1 hp | 745.7 W |
| 2 hp | 1491.4 W |
| 5 hp | 3728.5 W |
| 8 hp | 5965.6 W |
| 10 hp | 7457 W |
| 15 hp | 11185 W |
| 20 hp | 14914 W |
| 25 hp | 18642 W |
| 30 hp | 22371 W |
| 40 hp | 29828 W |
| 50 hp | 37285 W |
| 60 hp | 44742 W |
| 75 hp | 55927 W |
| 100 hp | 74570 W |
| 125 hp | 93212 W |
| 150 hp | 111855 W |
| 200 hp | 149140 W |
| 250 hp | 186425 W |
| 300 hp | 223710 W |
| 400 hp | 298280 W |
| 500 hp | 372850 W |
| 600 hp | 447420 W |
| 750 hp | 559275 W |
| 800 hp | 596560 W |
| 1000 hp | 745700 W |
| 1200 hp | 894840 W |
| 1500 hp | 1118550 W |
| 1800 hp | 1342260 W |
| 2000 hp | 1491400 W |
| 2500 hp | 1864250 W |
| 3000 hp | 2237100 W |
| 5000 hp | 3728499 W |
| 7500 hp | 5592749 W |
| 10000 hp | 7456999 W |
| 15000 hp | 11185498 W |
| 20000 hp | 14913997 W |
| 25000 hp | 18642497 W |
| 50000 hp | 37284994 W |
| 75000 hp | 55927490 W |
| 100000 hp | 74569987 W |
| 200000 hp | 149139974 W |
| 500000 hp | 372849936 W |
| 1000000 hp | 745699872 W |
| 2000000 hp | 1491399743 W |
| 5000000 hp | 3728499358 W |
| 10000000 hp | 7456998716 W |
| 100000000 hp | 74569987158 W |
| 1000000000 hp | 745699871582 W |
Real-world reference
A modern compact car produces 130–200 hp. A standard human can sustain about 0.1 hp indefinitely. In watts, that gives you: 1 hp = 745.7 W, 10 hp = 7457 W, 100 hp = 74570 W.
Frequently asked questions
- How many watts are in 1 mechanical horsepower?
- 1 mechanical horsepower equals 745.7 watts.
- How do I convert mechanical horsepower to watts?
- Multiply the mechanical horsepower value by 745.7. So x hp × 745.7 = the equivalent in W.
- What is 5 mechanical horsepower in watts?
- 5 mechanical horsepower equals 3728.5 watts.
- What is 10 mechanical horsepower in watts?
- 10 mechanical horsepower equals 7457 watts.
- What is 100 mechanical horsepower in watts?
- 100 mechanical horsepower equals 74570 watts.
- How do I convert back from watts to mechanical horsepower?
- Multiply the watt value by 0.00134102. For example, 1 W = 0.00134102 hp.
- Is the mechanical horsepower bigger than the watt?
- Yes. 1 mechanical horsepower is larger than 1 watt — specifically 745.7 times larger.
- Are these conversion factors exact?
- The underlying imperial/US unit definitions are exact; the displayed factor (745.7) is rounded for readability, and the browser computes using IEEE 754 double-precision arithmetic.
About the mechanical horsepower and the watt
The watt
The watt (W) is the SI derived unit of power, equal to one joule per second. It is the standard unit for the rated power of every electrical device and every modern engine specification outside automotive marketing.