Power Converter
Convert between watts, horsepower, kilowatts and more.
How to use Power Converter
Select your source unit
Click the 'From' dropdown menu at the top left and choose your starting unit (Watts, Horsepower, Kilowatts, BTU/h, or Joules/second). The dropdown displays all available power measurement units with their abbreviations.
Enter your value
Type your numerical value into the input field labeled 'Enter amount'. The field accepts decimals and whole numbers. You can paste values directly or use the up/down arrow buttons to adjust incrementally.
Choose your target unit
Click the 'To' dropdown menu on the right side and select your desired output unit (Watts, Horsepower, Kilowatts, BTU/h, or Joules/second). The conversion calculates automatically.
Copy or reset your result
View the converted value displayed in the result box. Click the 'Copy' button to copy the result to your clipboard, or click 'Reset' to clear all fields and start a new conversion.
Related Tools
Power converter: watts, kilowatts, horsepower, and BTU/hour
Power converter: watts, kilowatts, horsepower, and BTU/hour
Convert between watts, kilowatts, megawatts, mechanical horsepower, metric horsepower, electrical horsepower, and BTU/hour at ToolHQ's power converter, with a clear explanation of the three types of horsepower. Free, no account required.
Power measures the rate at which energy is transferred or converted, how much work is done per unit of time. Watts are the SI unit. Horsepower is used for engines and motors. BTU/hour appears in HVAC ratings. The conversion between them is straightforward, but horsepower has three different definitions that are easy to confuse.
ToolHQ's power converter handles all common power units and explains which horsepower definition applies to your context.
Key Takeaways
- 1 mechanical hp = 745.7 watts (used for US/UK car and engine ratings)
- 1 metric hp (PS/CV) = 735.5 watts (used for European vehicle specs)
- 1 electrical hp = 746 watts exactly (used for electric motor ratings)
- 1 kilowatt = 1.341 mechanical hp = 1,000 watts
- No data is stored or transmitted, all calculations run locally in your browser
The three types of horsepower, and which one applies
This is the most important thing to understand before converting horsepower. There are three commonly used definitions, and using the wrong one gives a slightly wrong answer:
| Horsepower type | Exact value | Used in |
|---|---|---|
| Mechanical hp (hp) | 745.699872 W | US and UK car engines, farm equipment, general machinery |
| Metric hp (PS, CV, pk) | 735.49875 W | European car specs, some Asian manufacturers |
| Electrical hp | 746 W exactly | Electric motors, US National Electrical Code |
How to tell which one applies:
- If the specification comes from a US or UK vehicle manufacturer, it is almost always mechanical hp
- If the specification comes from a European car listing (BMW, Mercedes, Volkswagen), it is metric hp (often labeled "PS" in German specs or "CV" in French/Italian ones)
- If the specification is for an electric motor (pump, compressor, fan), it is usually electrical hp
- The difference between mechanical and electrical hp is tiny (0.04%), for most practical purposes they are interchangeable
Origin of horsepower: James Watt, the 18th-century engineer, defined horsepower to help sell his steam engines. He calculated that a mill horse could do 33,000 foot-pounds of work per minute and used this as a benchmark to compare his engines. The metric version was independently defined later as 75 kilogram-force-meters per second (equivalent to 735.5 W).
All calculations run locally in your browser, no data is stored or transmitted.
Power conversion reference table
| Unit | Watts | Kilowatts | Mech. hp | BTU/hr |
|---|---|---|---|---|
| 1 Watt | 1 W | 0.001 kW | 0.001341 hp | 3.412 BTU/hr |
| 1 Kilowatt | 1,000 W | 1 kW | 1.341 hp | 3,412 BTU/hr |
| 1 Mechanical hp | 745.7 W | 0.7457 kW | 1 hp | 2,545 BTU/hr |
| 1 Metric hp (PS) | 735.5 W | 0.7355 kW | 0.9863 hp | 2,510 BTU/hr |
| 1 BTU/hour | 0.2931 W | 0.0003 kW | 0.000393 hp | 1 BTU/hr |
| 1 Megawatt | 1,000,000 W | 1,000 kW | 1,341 hp | 3,412,000 BTU/hr |
Key conversions:
- 100 hp (mechanical) = 74.57 kW = 74,570 W = 254,500 BTU/hr
- 200 PS (metric) = 147.1 kW = 147,100 W
- 1 ton of refrigeration = 12,000 BTU/hr = 3.517 kW
Mini-story 1: Alicia was shopping for a car and comparing two models online. A German BMW listed 306 PS and an American Chevrolet listed 305 hp. She wanted to know if the BMW actually had more power. She entered 306 PS (metric hp) into ToolHQ's power converter and got 225.8 kW. Then she entered 305 mechanical hp and got 227.4 kW. The Chevrolet was actually marginally more powerful in real terms, the similar-looking numbers masked the unit difference. She noted the BMW would also list around 301 mechanical hp if converted to the US rating.
Convert power units free at ToolHQ
How to use the ToolHQ power converter
- Go to the tool. Navigate to ToolHQ's power converter. No account or sign-up required.
- Enter your value. Type any number in the input field.
- Select your source unit. Choose from watts, kilowatts, megawatts, mechanical hp, metric hp, electrical hp, or BTU/hour.
- Read all results. The converter returns the equivalent in all supported units simultaneously.
Real-world power scale reference
| Device / system | Power output | Unit |
|---|---|---|
| LED light bulb | 8-15 W | Watts |
| Laptop computer | 30-65 W | Watts |
| Desktop computer (gaming) | 300-500 W | Watts |
| Microwave oven | 700-1,500 W | Watts |
| Electric vehicle charger (Level 2) | 7.2-22 kW | Kilowatts |
| Small car engine | 70-120 hp | Mechanical hp |
| Performance car engine | 300-600 hp | Mechanical hp |
| Window air conditioner (12,000 BTU) | 12,000 BTU/hr = 3.5 kW | kW / BTU/hr |
| Residential central HVAC | 24,000-60,000 BTU/hr | BTU/hr |
| Small wind turbine | 1-100 kW | Kilowatts |
| Large nuclear power plant unit | 1,000-1,600 MW | Megawatts |
HVAC note: Air conditioners and heat pumps are typically rated in BTU/hour in the US or kilowatts in most other countries. One "ton" of refrigeration capacity = 12,000 BTU/hr = 3.517 kW. A 3-ton home air conditioner runs at 36,000 BTU/hr = 10.55 kW.
For energy (power x time), ToolHQ's energy converter converts between kilowatt-hours, joules, BTU, and kilocalories.
Mini-story 2: Marcus was replacing a water pump for his irrigation system. The old pump's label showed 2 hp (no further specification). The replacement he was considering listed its output as 1,491 watts. He entered 2 mechanical hp into ToolHQ's power converter and got 1,491.4 watts, the replacement was essentially identical in power output. He also checked the electrical panel requirements: the pump at 1,491 W on 240V would draw about 6.2 amps, which fit within the 15-amp circuit he had available.
Frequently asked questions
Is metric horsepower the same as mechanical horsepower?
No. Mechanical horsepower (745.7 W) is used in the US and UK. Metric horsepower (735.5 W, often labeled PS, CV, or pk) is used in many European and Asian countries. They differ by about 1.4%. When comparing specs across different markets, always check which type is used.
What is BTU/hour used for?
BTU/hour (British Thermal Units per hour) is the standard power unit for HVAC systems in the US. It measures heat transfer rate. One BTU/hour equals 0.2931 watts. To convert a room air conditioner from BTU/hr to kilowatts, divide by 3,412.
How many watts are in 1 horsepower?
It depends on the type: mechanical hp = 745.7 W, metric hp = 735.5 W, electrical hp = 746 W. For most practical purposes, 746 W per horsepower is the standard approximation.
What is the difference between power and energy?
Power is the rate of energy transfer (watts = joules per second). Energy is the total amount transferred over time (kilowatt-hours = kilowatts x hours). A 100-watt light bulb (power) running for 10 hours uses 1 kilowatt-hour (energy).
Is the power converter free?
Yes. ToolHQ's power converter is completely free, with no account, no sign-up, and no usage limits.
The short version
Power conversion is mostly straightforward once you understand which horsepower definition applies. Mechanical hp (745.7 W) is the US and UK standard for vehicle and engine specs. Metric hp / PS (735.5 W) is the European standard. Electrical hp (746 W) is used for electric motors. For HVAC, BTU/hour is standard in the US, divide by 3,412 to get kilowatts. ToolHQ's power converter handles all three horsepower types alongside watts, kilowatts, megawatts, and BTU/hour, returning all equivalents from a single input.
For related tools, ToolHQ's energy converter converts kilowatt-hours, joules, BTU, and calories, and the electricity cost calculator calculates running costs from power consumption and usage time. Explore more converter tools at ToolHQ.
Convert power units free at ToolHQ