Horsepower (mechanical) to Watts (hp to W)

Formula

1 hp = 745.7 W

watts = horsepower (mechanical) × 745.6998716 — reverse: horsepower (mechanical) = watts × 0.00134102209

The factor is derived from the SI definitions of both units (base unit: W) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.

Worked examples

• 5 hp = 3728.5 W
• 12.5 hp = 9321.25 W
• 100 hp = 74570 W

Horsepower (mechanical) to watts conversion table

FAQ

How many watts are in one horsepower?

1 hp = 745.7 W. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

What is the formula to convert horsepower (mechanical) to watts?

Multiply the value in horsepower (mechanical) by 745.6998716: watts = horsepower (mechanical) × 745.6998716. For example, 5 hp = 3728.5 W.

How do I convert watts back to horsepower (mechanical)?

Multiply by the inverse factor 0.00134102209 (horsepower (mechanical) = watts × 0.00134102209), or use the watts-to-horsepower (mechanical) page.

Related conversions

• Watts to horsepower (mechanical) (reverse)
• Power Converter — all power units in one tool
• Horsepower (mechanical) to Kilowatts
• Kilowatts to Horsepower (mechanical)
• Kilowatts to Watts
• Watts to Kilowatts
• BTU per hour to Watts
• Watts to BTU per hour
• Metric horsepower (PS) to Kilowatts
• Kilowatts to Metric horsepower (PS)

Machine access

• API: GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=hp&to_unit=W
• MCP: server https://tttkmbb.com/mcp, tool convert_units with {"value":5,"from_unit":"hp","to_unit":"W"}
• Markdown: https://tttkmbb.com/conversion/hp-to-watts.md · JSON: https://tttkmbb.com/conversion/hp-to-watts.json (add ?value= for a result) · Units: /api/v1/units?quantity=power
• OpenAPI operationId: convert_units. Freshness: static. Authentication: none.

Sources

• NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors (standard)
• BIPM – The International System of Units (SI Brochure, 9th edition) (standard)
• Wikipedia – Conversion of units (reference)