Convert watts to hp

From: watt

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To: horsepower (metric)

Horsepower Type:

What this calculator does

This tool converts power between watts (W) and horsepower (HP) instantly. By default it converts watts → metric horsepower using the commonly used metric horsepower factor, and it can also convert back from HP to watts.

It’s useful for comparing electric motor ratings, generator output, engine power and any time you need a quick, accurate conversion.

(Why multiple answers appear on other sites: “horsepower” isn’t a single universal unit there are metric, mechanical/imperial, electrical, and boiler horsepower definitions. This calculator’s default is metric HP; formulas for other HP types are given below.)

How to use the calculator

Enter a number in the From box (your power value in watts, or in HP if you switched direction).
The conversion runs automatically as you type.
Use the switch button to toggle direction (Watts → HP or HP → Watts). The labels update so you always know which unit you’re entering and which you’re getting.
Select the desired Horsepower Type from the dropdown list (Metric, Mechanical, Electrical, or Boiler HP) to get accurate results for your specific application.

What’s happening behind the scenes

When converting Watts → HP, the calculator multiplies the watt value by a conversion factor (or, equivalently, divides by the watts-per-horsepower constant).
When converting HP → Watts, it uses the inverse factor (horsepower × watts-per-horsepower).
Our Convertor displays results to 10 decimal places for precision and readability.

Our current code uses the metric horsepower factor (1 metric HP = 735.49875 W) so the conversion used is: 1 W = 0.00135962162 metric HP. That is, the calculator computes:

hp(metric) = watts ÷ 735.49875
or
hp(metric) = watts × 0.00135962162

watts = hp(metric) × 735.49875

Those metric constants are the same factors used by popular converters and reference pages.

Common horsepower definitions & formulas

Different contexts use different horsepower definitions use the one that matches your spec sheet:

Metric horsepower (hp(M)) – common for many engine/motor specs
- 1 hp(M) = 735.49875 W
- hp(M) = watts / 735.49875.
Mechanical / Imperial horsepower (hp(I)) – often called “mechanical” or “hydraulic”
- 1 hp(I) ≈ 745.699872 W
- hp(I) = watts / 745.699872.
Electrical horsepower (hp(E)) – used sometimes for electrical systems
- 1 hp(E) = 746 W → hp(E) = watts / 746.
Boiler horsepower (hp(B) / hp(S)) – for steam/boiler rating
- 1 boiler HP ≈ 9,809.5 W → hp(boiler) = watts / 9809.5.

Tip: the differences are small for everyday numbers but matter when precision or standards compliance is required (industrial data sheets, engineering work, test reports).

Worked examples (exact arithmetic shown)

Convert 5,000 W to metric horsepower
hp(metric) = 5000 ÷ 735.49875 = 6.7981080865… → 6.7981080865 hp(M). (Calculator shows 10 decimals.)
Convert 5,000 W to mechanical horsepower
hp(mech) = 5000 ÷ 745.699872 = 6.7051104442… → 6.7051104442 hp(I).
Convert 7.5 hp(metric) to watts
watts = 7.5 × 735.49875 = 5,516.240625 W → 5,516.240625 W.

FAQs

Q.1 Which HP should I use for electric motors?

A: Usually metric HP or electrical HP are used for electric motors check the motor’s datasheet; many European motors use metric HP.

Q2. Are horsepower and watts interchangeable?
A: They both measure power but use different units; you must pick the correct horsepower definition before converting. The mathematical conversion is straightforward once the correct constant is chosen.

Q3. Why do conversion results differ between websites?
A: Because some sites show mechanical HP (≈745.7 W) while others use metric HP (≈735.5 W) both are correct, just different standards.

Sources