Horsepower to Kilowatts Calculator
Enter a horsepower value, choose the horsepower type, and instantly convert hp to kW.
Formula: kW = hp × conversion factor
What this hp to kW calculator does
This horsepower to kilowatts calculator helps you convert power values quickly and accurately. If you work with electric motors, pumps, compressors, generators, HVAC systems, or industrial equipment, you probably move between horsepower (hp) and kilowatts (kW) all the time. Instead of using a rough estimate, this tool gives you precise conversion values in seconds.
Many people assume there is only one horsepower definition. In practice, there are several standards, and that changes the final kilowatt result. That is why this calculator includes common horsepower types: mechanical horsepower, metric horsepower, electrical horsepower, and boiler horsepower.
hp to kW conversion formula
The general conversion is simple:
kW = hp × factor
The factor depends on the horsepower standard you are using. Here are the most common values:
| Horsepower Type | Symbol | Conversion to kW |
|---|---|---|
| Mechanical horsepower | hp | 1 hp = 0.745699872 kW |
| Metric horsepower | PS / CV | 1 PS = 0.73549875 kW |
| Electrical horsepower | hpE | 1 hpE = 0.746 kW |
| Boiler horsepower | BHP | 1 BHP = 9.8095 kW |
Quick examples
Example 1: Motor nameplate in mechanical hp
If a motor is rated at 10 hp (mechanical):
kW = 10 × 0.745699872 = 7.45699872 kW
Rounded to practical engineering precision: 7.46 kW.
Example 2: Vehicle power in metric hp
If an engine output is 150 PS:
kW = 150 × 0.73549875 = 110.3248125 kW
Rounded: 110.32 kW.
Example 3: Boiler system capacity
If a boiler is rated at 20 boiler hp:
kW = 20 × 9.8095 = 196.19 kW
Why accurate conversion matters
- Correct equipment sizing: Avoid underpowered or oversized systems.
- Energy planning: Estimate electrical demand and operating costs more reliably.
- Specification matching: Compare products listed in different unit systems.
- Compliance and documentation: Many technical reports and standards require SI units like kW.
Common mistakes to avoid
- Using the wrong horsepower type without checking the source document.
- Rounding too early before final calculation.
- Confusing boiler horsepower with mechanical horsepower (they differ dramatically).
- Ignoring real-world efficiency when estimating electrical input power.
hp to kW vs real electrical consumption
Converting hp to kW gives you power equivalence, not always actual input energy draw. For electric motors, actual input power depends on motor efficiency and power factor. For planning electrical circuits, include these values instead of relying only on nameplate horsepower conversion.
A practical estimate for electric input might look like this:
- Output power (kW) from hp conversion
- Input power (kW) = Output power / Efficiency
- Then account for power factor if you need kVA
Frequently asked questions
Is 1 hp exactly 0.746 kW?
Not always. That value is very close and often used for quick estimation. Exact conversion depends on the horsepower standard. Mechanical hp is 0.745699872 kW, while electrical hp is 0.746 kW.
Which conversion should I use for motors?
Most motor ratings in the U.S. are based on mechanical horsepower, so 1 hp = 0.745699872 kW is typically appropriate unless the manufacturer states otherwise.
Can I use this calculator for engine power?
Yes. Just choose the horsepower type that matches your data source (mechanical hp or metric hp are common for engines depending on region).
Final takeaway
When converting horsepower to kilowatts, the method is easy, but choosing the correct horsepower definition is essential. Use the calculator above for fast, accurate hp to kW conversion, then apply suitable rounding for your project, report, or equipment selection process.