Convert between watts, kilowatts, horsepower and BTU/h.
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How do you convert watts to horsepower and other power units?
Each value is converted to watts, then to the target unit; for example, 1 mechanical horsepower = 745.7 W and 1 metric horsepower (PS) = 735.5 W. So 100 hp = 74.57 kW = 254,407 BTU/h. Mechanical and metric horsepower differ slightly, and BTU/h is common for heating and air-conditioning ratings.
Understanding your result
Mechanical (imperial) horsepower and metric horsepower (PS) differ slightly. BTU/h is common for heating and air-conditioning ratings.
Formula and method
Each value is converted to watts, then to the target unit. For example, 1 mechanical horsepower = 745.7 W and 1 metric horsepower (PS) = 735.5 W.
Assumptions and limitations
The tool converts a rate of power, not energy — for total energy over time use a kilowatt-hour figure instead. It distinguishes mechanical horsepower (745.7 W) from metric horsepower or PS (735.5 W); manufacturers in different markets quote different definitions, so an engine's "horsepower" can shift slightly depending on the standard used.
Worked example
100 hp = 74.57 kW = 254,407 BTU/h.
Common power conversions
| Convert | Equals |
|---|---|
| 1 mechanical hp | 0.7457 kW |
| 1 kW | 1.34102 mechanical hp |
| 1 metric hp (PS) | 735.499 watts |
| 1 kW | 3,412.14 BTU/hour |
| 1 megawatt | 1,000 kilowatts |
| 100 mechanical hp | 74.57 kW |
| 1 kW | 1.35962 metric hp (PS) |
| 1 watt | 3.41214 BTU/hour |
How to use this tool
- Enter the power value.
- Choose the units to convert from and to.
- Read the result and the full unit table.
Common mistakes to avoid
- Mixing up energy (watt-hours) with power (watts) — power is the rate of energy use.
About the Power Converter
Convert power between watts, kilowatts, horsepower and BTU per hour. Enter a value and see every unit at once.
Who should use this tool
Car and motorcycle enthusiasts comparing engine output, engineers and electricians working in watts and kilowatts, and anyone reading appliance or HVAC ratings in horsepower or BTU per hour. It covers watts, kilowatts, megawatts, mechanical and metric horsepower and BTU/hour.
Benefits
- Separates mechanical and metric horsepower, which are often confused
- Bridges electrical (kW), automotive (hp/PS) and heating (BTU/h) units
- Exact conversion factors for consistent, comparable figures
- Instant and offline with no account needed
Practical use cases
- Comparing car engine power quoted in hp, PS or kW
- Reading an appliance or motor rating in watts and kilowatts
- Sizing heating or air-conditioning stated in BTU per hour
- Converting a generator output between kilowatts and horsepower
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Frequently asked questions
How many kW is 1 hp?
One mechanical horsepower is about 0.7457 kW.
What is the difference between hp and PS?
PS is metric horsepower (735.5 W); mechanical hp is 745.7 W, so they differ by about 1.4%.
How many kilowatts is one horsepower?
One mechanical horsepower equals 0.7457 kilowatts (745.7 watts). Metric horsepower (PS), common in Europe, is slightly less at 0.7355 kW, so a 100 hp engine is about 74.6 kW.