Calculation reviewed: 4 October 2026 · Engineering Desk Tools
How to use the HP to kW & kW to HP calculator
Convert power between kilowatts and mechanical, metric or electric horsepower. Start with measurements or documented values for the equipment and reporting period you actually want to assess. The calculator does not fill in a typical installation for you. Its blank fields help keep a demonstration value from being mistaken for your own operating data.
Choose the required options, enter the values in the labelled units and select Calculate. If a field is rejected, check its range and unit before changing it. The result is accompanied by the equation and assumptions so you can decide whether it answers your engineering question.
Inputs and measurement basis
- Conversion. Pick which way to convert.
- Horsepower definition. Mechanical HP (550 ft·lbf/s), metric PS or electric HP. Check which one the nameplate uses.
- Power in the selected input unit. The value to convert, in the input unit of the chosen conversion.
Record the measurement source and operating condition. Retain unrounded values for verification.
Method and interpretation
Horsepower has several definitions. Mechanical horsepower, metric horsepower and electrical horsepower differ slightly, so specify the definition before comparing nameplates or documentation. This tool changes units only: the physical power being described must remain the same on both sides of the conversion.
kW = HP × conversion factor. HP = kW / conversion factor. Factors: mechanical 0.7456999; metric 0.7354988; electric 0.746.
Choose the horsepower definition stated on the equipment data. This is a unit conversion only: it does not convert motor shaft output to electrical input or account for efficiency. Factors follow the rounded NIST table.
Worked example
This example does not populate the form. Enter your own installation data.
Calculated result: 3.7285 kW. Power unit conversion · mechanical horsepower definition
Check the arithmetic independently using the displayed equation. Retain intermediate precision and compare the final value with your equipment documentation.
Quick-reference table
These illustrative rows retain the worked example assumptions except for the varied input. They are not certified ratings or manufacturer data. Use the form for intermediate values.
Common mistakes
Mixing metric PS with mechanical HP; assuming electrical and mechanical input/output are interchangeable; rounding a converted value too early in a longer calculation. Before relying on the output, check the decimal format, unit scale and source of each value. Recheck unusual results against the formula.
Frequently asked questions
Are the example values used automatically?
No. Inputs remain blank when the tool opens or when you clear them. The worked example and table are reading material below the calculator. Enter the actual values you want to check each time, and label saved reports so their context is not lost.
What does the result mean?
The result is the same power expressed in the other unit under the horsepower definition you chose. It does not account for efficiency or convert shaft output to electrical input.
Can I use a zero or a negative value?
The allowed range follows the meaning of each input. A divisor needs a positive value; other fields may allow zero. Check the form labels and error message rather than forcing an invalid value. A rejected input must be corrected before a result can be shown.
Is this a final design or equipment approval?
No. Choose the horsepower definition stated on the equipment data. This is a unit conversion only: it does not convert motor shaft output to electrical input or account for efficiency. Factors follow the rounded NIST table. Use the calculation as support for a checked decision, and review equipment documentation and applicable requirements before changing an installation or operating setting.
How can I save or share a calculation?
Calculate first, then use Copy result or Print report. Some maintenance tools also provide a CSV summary. Reports contain your own entered data, so review them before sharing. You can share the public page URL without including plant records or confidential measurements.
How do I report an unexpected result?
Use the Contact page and include the tool URL, input values, units, expected output and the reference you used. Explain the measurement basis. Exclude confidential information.
Related tools and records
Use related calculations with consistent units, periods and equipment scope.
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