What is the difference between mechanical, electrical, and metric horsepower?

Mechanical (imperial) horsepower is 745.69987 W and is the standard in the United States for most engines. Electrical horsepower is exactly 746 W and is used for electric motors in the US. Metric horsepower (PS or CV) is 735.49875 W and is common in Europe and Asia for vehicle ratings.

How many watts is 1 horsepower?

One mechanical horsepower equals 745.69987 watts, one electrical horsepower equals exactly 746 watts, and one metric horsepower (PS) equals 735.49875 watts.

Why do car specs sometimes list different HP values?

European manufacturers traditionally use metric horsepower (PS), while American manufacturers use mechanical horsepower. The difference is small — about 1.4% — but it explains why the same car can show slightly different numbers in different markets.

Can I convert horsepower back to watts?

Yes. Multiply mechanical hp by 745.69987, electrical hp by 746, or metric hp (PS) by 735.49875 to get watts.

Is this tool accurate enough for engineering calculations?

The conversion factors used match the ISO and IEEE standards to six significant figures, which is sufficient for most practical engineering and specification work.

Watts to Horsepower Converter

Name: Watts to Horsepower Converter
Availability: InStock
Author: Nham Vu

Enter watts to instantly convert to mechanical, electrical, and metric horsepower with a common power reference table.

Enter Power in Watts

Watts (W)

Quick presets

Horsepower Results

Enter a watt value on the left to see results.

Common Power Reference

Device / Motor	Watts	hp (mech)	PS (metric)

Copied to clipboard

Summary

Enter watts to instantly convert to mechanical, electrical, and metric horsepower with a common power reference table.

How it works

Enter a power value in watts in the input field.
The tool multiplies the watt value by the conversion factor for each horsepower standard.
Mechanical hp uses 1 hp = 745.69987 W; electrical hp uses 1 hp(E) = 746 W; metric hp uses 1 PS = 735.49875 W.
All three results update instantly as you type.
Use the reference table below to look up common appliance and motor ratings.

Use cases

Convert electric motor specs from watts to horsepower for equipment selection.
Compare generator output ratings between metric and mechanical standards.
Verify vehicle engine power values across different regional HP standards.
Convert HVAC or pump motor ratings listed in watts to familiar horsepower figures.
Cross-check product datasheets that mix watt and horsepower units.
Look up where a specific appliance or motor falls in the common reference table.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu