# Watts to Horsepower (mechanical) (W to hp)

> Convert watts to horsepower (mechanical): 1 W = 0.00134102 hp. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `watts-to-hp` · Quantity: Power (`power`, base unit W) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/watts-to-hp · This document: https://tttkmbb.com/conversion/watts-to-hp.md · JSON: https://tttkmbb.com/conversion/watts-to-hp.json (add `?value=` for a result)

## Formula

- `1 W = 0.00134102 hp`
- `horsepower (mechanical) = watts × 0.00134102209`
- Reverse: `watts = horsepower (mechanical) × 745.6998716`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 W = 0.00670511 hp
- 12.5 W = 0.0167628 hp
- 100 W = 0.134102 hp

## Conversion table

| Watts (W) | Horsepower (mechanical) (hp) |
| --- | --- |
| 1 | 0.00134102 |
| 2 | 0.00268204 |
| 3 | 0.00402307 |
| 4 | 0.00536409 |
| 5 | 0.00670511 |
| 6 | 0.00804613 |
| 7 | 0.00938715 |
| 8 | 0.0107282 |
| 9 | 0.0120692 |
| 10 | 0.0134102 |
| 15 | 0.0201153 |
| 20 | 0.0268204 |
| 25 | 0.0335256 |
| 30 | 0.0402307 |
| 40 | 0.0536409 |
| 50 | 0.0670511 |
| 75 | 0.100577 |
| 100 | 0.134102 |
| 200 | 0.268204 |
| 250 | 0.335256 |
| 500 | 0.670511 |
| 1000 | 1.34102 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=W&to_unit=hp` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"W","to_unit":"hp"}`
- All power units: https://tttkmbb.com/api/v1/units?quantity=power · full converter: [Power Converter](https://tttkmbb.com/conversion/power.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many horsepower (mechanical) are in one watt?**

1 W = 0.00134102 hp. 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 watts to horsepower (mechanical)?**

Multiply the value in watts by 0.00134102209: horsepower (mechanical) = watts × 0.00134102209. For example, 5 W = 0.00670511 hp.

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

Multiply by the inverse factor 745.6998716 (watts = horsepower (mechanical) × 745.6998716), or use the horsepower (mechanical)-to-watts page.

## Related conversions

- [Horsepower (mechanical) to watts](https://tttkmbb.com/conversion/hp-to-watts.md) (reverse)
- [Horsepower (mechanical) to Kilowatts](https://tttkmbb.com/conversion/hp-to-kw.md)
- [Kilowatts to Horsepower (mechanical)](https://tttkmbb.com/conversion/kw-to-hp.md)
- [Kilowatts to Watts](https://tttkmbb.com/conversion/kw-to-watts.md)
- [Watts to Kilowatts](https://tttkmbb.com/conversion/watts-to-kw.md)
- [BTU per hour to Watts](https://tttkmbb.com/conversion/btu-per-hour-to-watts.md)
- [Watts to BTU per hour](https://tttkmbb.com/conversion/watts-to-btu-per-hour.md)
- [Metric horsepower (PS) to Kilowatts](https://tttkmbb.com/conversion/ps-to-kw.md)
- [Kilowatts to Metric horsepower (PS)](https://tttkmbb.com/conversion/kw-to-ps.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)