Use kW → HP to convert a kilowatt rating into horsepower, or HP → kW to go the other direction back into kilowatts.
Enter power in kilowatts. Formula: HP = kW ÷ conversion factor (factor depends on the type selected below).
The U.S. and Canadian standard (NEMA). Used on most North American motor and engine nameplates.
Used across the EU, Asia, and Latin America (IEC/ISO), and on most automotive spec sheets outside North America.
A narrower U.S. convention for electric motor output ratings (IEC 60034). Nearly identical to Mechanical.
This chart shows what your entered power equals in all three horsepower types at once — useful because different equipment specs may use any of the three.
Results are for reference and estimation only. Verify all values before use in any electrical or mechanical design work. See full disclaimer below.
Common motor sizes in kilowatts, mapped to Mechanical and Metric horsepower, with a typical real-world application for each. Use this to sanity-check a calculated result at a glance.
| kW | Mech. HP | Metric HP (PS) | Typical Application |
|---|---|---|---|
| 0.25 | 0.335 | 0.340 | Fractional pumps, small fans, HVAC dampers |
| 0.37 | 0.496 | 0.503 | Bench grinders, small compressors (≈½ HP class) |
| 0.55 | 0.738 | 0.748 | Sump pumps, sewing machines (≈¾ HP class) |
| 0.75 | 1.006 | 1.020 | Residential pool pumps (≈1 HP class) |
| 1.5 | 2.012 | 2.039 | Garage door openers, grain augers (≈2 HP class) |
| 2.2 | 2.951 | 2.991 | Drill presses, small compressors (≈3 HP class) |
| 5.5 | 7.376 | 7.478 | Centrifugal pumps (≈7.5 HP class) |
| 11 | 14.752 | 14.956 | HVAC chillers, large blowers (≈15 HP class) |
| 22 | 29.503 | 29.912 | Conveyor drives (≈30 HP class) |
| 55 | 73.759 | 74.779 | Industrial mixers, mine ventilation fans (≈75 HP class) |
A deeper look at why "horsepower" isn't just one number, and how to read a motor nameplate correctly — written for students and job-site reference alike.
Mechanical Horsepower (745.7 W)
Also called Imperial horsepower, this is the standard used across the United States and Canada. It traces back to James Watt's original 18th-century comparison of steam engine output to the work of a draft horse, and was later codified by NEMA (the National Electrical Manufacturers Association) for U.S. motor nameplates. If a motor catalog is from a NEMA manufacturer, this is almost always the HP value being listed.
Metric Horsepower / PS (735.5 W)
Known as PS in German, CV in French and Spanish, this standard is used across the European Union, most of Asia, and Latin America. It's defined under ISO 1000 and DIN 66036, and is the figure you'll see on most automotive spec sheets published outside North America. It is about 1.4% smaller than mechanical horsepower — small per unit, but it adds up on larger motors.
Electric Horsepower (746.0 W)
Defined under IEC 60034, this is a narrower convention used specifically for electric motor output ratings in some North American contexts. It differs from mechanical horsepower by only about 0.04% — close enough that the two are often used interchangeably in practice, but it exists as its own defined standard.
| Type | Watts per 1 HP | ÷ Factor | Common Region / Standard | Typical Use |
|---|---|---|---|---|
| Mechanical | 745.7 W | 0.7457 | U.S., Canada — NEMA MG1 | NEMA motor nameplates |
| Metric (PS) | 735.5 W | 0.7355 | EU, Asia, Latin America — ISO 1000 | IEC motor & automotive specs |
| Electric | 746.0 W | 0.7460 | N. America — IEC 60034 | Electric motor output ratings |
Reading a NEMA vs IEC Nameplate
NEMA-rated motors — common across the U.S. and Canada — list output power in horsepower directly on the nameplate, generally using the mechanical HP standard. IEC-rated motors — common across Europe, Asia, and most of the rest of the world — list output power in kilowatts on the nameplate, with metric horsepower used mainly in catalogs and automotive contexts rather than the nameplate itself. When matching a NEMA motor to an IEC replacement, convert using the mechanical HP formula; the two are close enough (within roughly 2%) that direct substitution usually works if voltage, frame size, and mounting also match.
Output Power vs Input Power
The kW or HP value on a nameplate is the rated output (shaft) power — the mechanical work the motor delivers. The actual electrical input power draw is always somewhat higher, because no motor is 100% efficient. For a motor that is roughly 90% efficient, input kW is approximately output kW divided by 0.90. This matters when sizing breakers, wiring, or a VFD — protection should be based on input current, not the nameplate HP or kW value alone.
This guide is provided for educational and reference purposes. Always confirm motor specifications against the actual manufacturer nameplate or datasheet before sizing, ordering, or installing equipment.