How to use the Power Converter
- Type the power value.
- Choose the unit you are converting from.
- Choose the unit you want.
- Read the result, and use the reference table for common values.
Formula used
Result = Value × (watts per source unit ÷ watts per target unit). 1 mechanical hp = 745.6999 W, 1 metric horsepower (PS) = 735.49875 W, 1 BTU/h = 0.29307 W.
Worked example
Here is the Power Converter worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Value | 100 |
| From | Horsepower (mechanical, hp) |
| To | Kilowatts (kW) |
| Result | |
| Converted value | 74.569987 |
| Conversion rate | 1 hp = 0.74569987 kW |
Quick reference table
Common values converted with the units selected above.
| From | To |
|---|---|
| 1 hp | 0.74569987 kW |
| 5 hp | 3.7284994 kW |
| 10 hp | 7.4569987 kW |
| 50 hp | 37.284994 kW |
| 100 hp | 74.569987 kW |
| 500 hp | 372.84994 kW |
Horsepower, in its two forms
Mechanical horsepower (hp) is 745.699872 W. Metric horsepower (PS, CV or pk) is 735.49875 W, slightly smaller. Cars in Europe and Asia are often rated in PS while US specifications use hp, so a "150 PS" engine is about 147.948011 hp.
A 100 hp engine is 74.569987 kW. To go the other way, 100 kW is 134.102209 hp.
Watts and kilowatts at home
Appliances list their power: a kettle at 2,000 W is 2 kW, a laptop charger about 65 W and an LED bulb 9 W. Multiply by the time used to get energy, and by your tariff to get cost: a 2 kW kettle running for 3 minutes uses 0.1 kWh.
The energy converter and the electricity-related calculators on this site help with that next step.
Heating and cooling in BTU per hour
Air conditioners and furnaces are often rated in BTU per hour. One BTU/h is 0.293071 W, so a 12,000 BTU/h air conditioner has a cooling capacity of 3.516853 kW.
That figure is cooling output, not the electricity it uses. An efficient unit uses a third or less of that in electrical power.
Large and small scales
Power stations are measured in megawatts: 1 MW is 1,000 kW or 1,341.02209 hp. A large wind turbine is a few MW and a big power station can be over 1,000 MW.
Human power is much smaller. A fit cyclist can sustain around 200 watts for an hour, about a quarter of a horsepower.
Power in everyday context
A phone charger delivers about 5 to 30 W, a laptop 45 to 100 W, a microwave around 800 to 1,200 W and an electric shower or oven several kilowatts. A small car engine produces about 70 to 100 kW and a large electric car motor can exceed 200 kW.
When comparing engines, remember that horsepower alone does not describe performance. Torque, weight, gearing and how long the power can be held all matter, and electric motors reach their peak output very differently from petrol engines.
Frequently asked questions
How many watts is one horsepower?
Mechanical horsepower is 745.699872 watts.
What is the difference between hp and PS?
PS (metric horsepower) is 735.49875 W and hp is 745.699872 W, so one hp is about 1.014 PS.
How many kW is 1 hp?
About 0.7457 kW.
What is the difference between kW and kWh?
kW is power, a rate. kWh is energy, an amount: power multiplied by time.
How much is a ton of air conditioning?
A ton of cooling is 12,000 BTU per hour, which is 3.516853 kW of cooling.
How do I convert BTU/h to watts?
Multiply by 0.29307. For example, 5,000 BTU/h is about 1,465 W.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.