Convert watt to horsepower (mechanical).

Convert watt (W) to horsepower (mechanical) (hp). This is a fixed-ratio conversion — multiply the input by the factor below.

Formula

hp = W × 0.00134102

Reference values

Things to watch for

• 1 HP (mechanical) = 745.7 W. Metric HP (PS) = 735.5 W. Boiler HP is yet another value. Be specific.
• A '1 ton AC unit' is a power rating: 1 ton ≈ 3.517 kW of cooling capacity (from melting one ton of ice per day).
• BTU/h ≈ 0.293 W. A 12,000 BTU/h AC = 3.5 kW = 1 ton.

What is a watt?

The watt is the SI unit of power, defined as one joule per second. Light bulbs, appliances, electrical loads, and small motors.

What is a horsepower (mechanical)?

One mechanical horsepower equals about 745.7 watts. The "metric horsepower" (PS, CV) is slightly different at 735.5 W. Engine output ratings (cars, motorcycles, lawnmowers), pump ratings, and industrial machinery.

Real-world examples of W

To put the unit in perspective, here are a few real-world examples. 60 W is an incandescent reading lamp; 100 W is a typical desktop computer; and 1000 W is a microwave or hair dryer.

How to convert watt to horsepower (mechanical)

To convert a value from watt (W) to horsepower (mechanical) (hp), apply the conversion factor shown in the formula above. The calculation is the same whether you do it by hand, in a spreadsheet, or with the live converter on this page.

Steps:

1. Take your input value in W.
2. Apply the formula hp = W × 0.00134102.
3. The result is your value in hp.

For repeated calculations, save the formula in a spreadsheet or use the live converter at the top of this page — it handles the math automatically and displays the result as you type.

Frequently asked questions

How do I convert W to hp?

Apply the formula W → hp shown above, or just type your value into the converter at the top of this page. The result updates instantly.

Which is bigger, W or hp?

This depends on the conversion ratio in the formula. If the factor multiplied by your value gives a larger number, then hp is the smaller unit (so it takes more of them to express the same quantity). If the result is smaller, then hp is the larger unit.

When would I use W versus hp?

Both units measure power, so the choice depends on context. Watt is typically used for engines, electrical loads, and HVAC equipment; horsepower (mechanical) similarly. Most professional fields standardize on one or the other based on regional conventions or technical tradition.

How precise is this W to hp conversion?

The conversion factor shown is the internationally defined exact value (or the best-published approximation if the relationship is irrational, like degrees-to-radians). The live converter on this page uses double-precision floating-point math, accurate to about 15 significant digits — far beyond any practical engineering need.

Is the conversion ratio exact, or an approximation?

Most unit conversions between SI metric units, and between SI and US customary units, have been formally defined as exact values since the 1959 international yard-pound agreement and subsequent SI redefinitions. Exceptions are unit pairs that involve irrational numbers (radians, e.g.) or empirical conversions (like food calories, which depend on temperature). When in doubt, consult the formula at the top of this page.

Related conversions

See also