Watts to Horsepower Converter
Convert watts to horsepower for motors, appliances, and engineering power ratings.
How It Works
Formula: W to hp = value ÷ 745.699872
Example: 1000 W = 1.341022 hp
Note: 1 mechanical horsepower equals 745.7 watts, the conversion for US motor and appliance power ratings.
Common Uses
Quick Conversion Table
| W | hp |
|---|---|
| 1 | 0.0013 |
| 5 | 0.0067 |
| 10 | 0.0134 |
| 50 | 0.0671 |
| 100 | 0.1341 |
| 500 | 0.6705 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.0001 hp
Precision Guidance
For motors, round to 2 decimals. For engineering, keep 3-4 decimals.
Common Mistakes
Mechanical horsepower (745.7 W) differs from metric horsepower/PS (735.5 W). Confirm the standard a spec uses.
Frequently Asked Questions
What is 1000 watts in horsepower?
1000 watts equals 1.3410 horsepower using the conversion 1 hp = 745.7 W.
How do I convert watts to hp?
Divide the watt value by 745.7. For example, 1500 W ÷ 745.7 = 2.012 hp.
How many watts is 1 hp?
1 mechanical horsepower equals 745.7 watts.
Is this mechanical or metric horsepower?
This uses mechanical horsepower (745.7 W). Metric horsepower (PS) is 735.5 W.
Deep Dive Guide
Watts to HP: Electric Motor and Tool Power for US Buyers
Convert watts to hp for US electric motors, shop tools, and appliances. 1 watt equals 0.00134102 hp, and 1 mechanical horsepower equals 745.7 watts.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 mechanical horsepower (hp) = 745.6998715823 watts (exact, 550 ft·lbf/s)
- EXACT1 British thermal unit, IT (Btu) = 1055.05585262 joules (exact)
- EXACT1 Btu/h = 0.293071070172 watts (exact, Btu ÷ 3600 s)
- EXACT1 watt (W) = 1 joule per second (definition)
Common Pitfalls & How to Avoid Them
Mechanical hp vs. metric hp
Mechanical hp = 745.7 W. Metric (PS) hp = 735.5 W and electrical hp = 746 W. Engine specs may use any of these; always check which.
Btu IT vs. thermochemical
UnitFig uses the IT Btu (1055.05585262 J). The thermochemical Btu (1054.35 J) is ~0.07% smaller and used in some chemistry contexts — keep them separate.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy