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The motor's mechanical output in horsepower.
Motor nameplates state mechanical output at the shaft. The electrical input is higher by the motor's efficiency, so a 5 hp motor at 88% efficiency draws about 4.24 kW rather than 3.73 kW.
Mechanical output
3.728 kW
Converted using an exact defined factor of 0.7456998715822702 kW per hp. This is shaft output. Electrical input is higher — divide by the motor's efficiency to get the draw.
- Conversion factor applied
- 0.75 kW per hp
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Horsepower to kW Calculator: 3.73 kW — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Mechanical horsepower is defined as 550 ft-lbf/s = 745.699872 W exactly
- Metric horsepower (PS) differs at 735.49875 W and is not used here
Inputs used
- Motor rating (hp)
- 5
Intermediate steps
- Conversion factor applied
- 0.75 kW per hp
Confidence note: Converted using an exact defined factor of 0.7456998715822702 kW per hp. This is shaft output. Electrical input is higher — divide by the motor's efficiency to get the draw.
What this calculation does not cover
- This converts shaft output, not electrical demand. No motor efficiency, no power factor and no phase count enter the arithmetic, so the result is not the kW drawn from the supply, not kVA, and not a current. It is not a load calculation and cannot size a cable, a breaker or a generator.
- Nameplate horsepower is a rating, not a duty. A motor driving a light load draws well below its plate, and one with a service factor above 1.0 may be run continuously above it, so the converted figure describes the label rather than what the machine is actually doing.
- Starting behaviour sits outside the conversion. A direct-on-line induction motor draws several times its running current for the first few seconds, which governs protective device selection, voltage drop and generator sizing, and none of that is visible in a kilowatt figure.
- The factor applied is mechanical horsepower, and the calculator cannot tell what your nameplate means. Metric horsepower (PS, CV, pk on continental European machinery) is about 1.4% lower, and boiler horsepower is a different quantity altogether at roughly 9.8 kW, so entering either returns a result wrong by that margin or by more than a factor of ten.
- Nothing between the shaft and the driven machine is accounted for: belt, gearbox and coupling losses, and the gap between the motor's rating and the power a pump, fan or compressor actually absorbs. Selecting driven equipment needs its own duty point, not the motor's plate.
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This result is a specification — 3.728 kW — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations2
- Mechanical horsepower is defined as 550 ft-lbf/s = 745.699872 W exactly
- Metric horsepower (PS) differs at 735.49875 W and is not used here
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Plant and machinery bought from American suppliers arrives rated in horsepower while the electrical design around it works in kilowatts, so pump, compressor and machine-tool selection routinely needs this step. Two details cause real errors. The first is which horsepower: mechanical horsepower is 745.6999 W, but metric horsepower — still quoted on some European equipment as PS or CV — is 735.49875 W, roughly 1.4% adrift. The second is that horsepower describes what leaves the shaft, not what enters the terminals. A motor is not perfectly efficient, so the electrical demand is the converted figure divided by the efficiency, and sizing a supply from the shaft rating alone will leave the circuit short. For anything beyond rough comparison, take the running current straight from the nameplate.