Power Converter - Watts, kW, MW, HP, BTU/s, Tons of Refrigeration
Free online power unit converter. Instantly convert between watts, kilowatts, megawatts, gigawatts, milliwatts, horsepower, BTU per second, and refrigeration tons.
Input Power
Converted Power
What Is a Power Converter and Why Do You Need One?
A power converter (also called a power unit converter or watt converter) is an online tool that instantly translates measurements between different units of power. Power is the rate at which energy is transferred or work is done, measured in watts (W) in the International System of Units (SI). Whether you need to convert watts to horsepower, convert kilowatts to BTU per second, convert megawatts to gigawatts, or work with specialized units like tons of refrigeration for HVAC systems, this free power conversion calculator provides accurate, instant results.
Power measurements are fundamental in electrical engineering, mechanical engineering, automotive performance, energy production, HVAC design, and everyday appliance ratings. A light bulb might be rated at 60 W, a car engine at 300 hp (≈224 kW), a power plant at 500 MW, and an air conditioner at 5 tons of refrigeration (≈17.6 kW). Different industries and countries use different units: the US commonly uses horsepower for engines and tons of refrigeration for cooling; Europe uses kilowatts; large‑scale energy uses megawatts and gigawatts. Our online power unit converter bridges all these systems in one place.
This free power converter operates entirely within your browser - no data is sent to any server, ensuring your privacy and enabling offline use. It supports 8 power units: watts, kilowatts, megawatts, gigawatts, milliwatts, horsepower, BTU per second, and tons of refrigeration. Whether you are an electrician sizing a generator, a car enthusiast comparing engine outputs, a student solving physics problems, or an HVAC technician calculating cooling loads, this tool is your go‑to solution.
How to Use This Free Online Power Converter
Using this watt to hp converter is simple. Follow these steps to get accurate conversions instantly:
- Enter the value: Type the numeric power value you wish to convert. The tool accepts positive numbers, decimals, and large values up to 10¹⁵.
- Select the source unit: Choose the unit of your input value from the "From Unit" dropdown menu. Options include Watts (W), Kilowatts (kW), Megawatts (MW), Gigawatts (GW), Milliwatts (mW), Horsepower (hp), BTU per second (BTU/s), and Ton of Refrigeration (TR).
- Select the target unit: Choose the unit you want to convert to from the "To Unit" dropdown.
- View the result: The converted value appears instantly in the output panel. You can copy the result to your clipboard with a single click.
- Use additional features: Click "Swap Units" to reverse the conversion direction, "Clear" to reset all fields, or the fullscreen button for an expanded view.
The kW to hp converter automatically performs conversions as you type, so you don't need to click a separate convert button unless you prefer manual control. Your recent selections are saved locally for up to 30 days, making it easy to continue your work across sessions.
All Supported Power Units - Complete Reference Table
Our power unit converter supports 8 essential power units spanning metric, imperial, and HVAC-specific systems. Below is a complete reference table showing each unit, its symbol, exact conversion factor to watts, and typical applications.
| Unit | Symbol | Value in Watts (exact) | Common Applications |
|---|---|---|---|
| Milliwatt | mW | 0.001 | Laser pointers, small sensors, LED indicators |
| Watt | W | 1 | SI base unit. Light bulbs (5‑100 W), phone chargers, small appliances |
| Kilowatt | kW | 1000 | Household appliances (1.5‑5 kW), electric car motors (50‑200 kW), small generators |
| Megawatt | MW | 1,000,000 | Power plant output (500‑1500 MW), large ship engines, wind turbines (2‑10 MW) |
| Gigawatt | GW | 1,000,000,000 | National grid capacity (10‑100 GW), large hydroelectric dams (Three Gorges: 22.5 GW) |
| Horsepower (mechanical) | hp | 745.699872 | Car engines (100‑400 hp), lawn mowers, industrial motors |
| BTU per second | BTU/s | 1055.05585262 | High‑power heating systems, industrial burners, thermal power |
| Ton of Refrigeration | TR | 3516.8528420667 | Air conditioning systems, chillers, refrigeration capacity (1 TR = 12,000 BTU/hr) |
Understanding Power Units - From Milliwatts to Gigawatts
Watts (W) - The SI Unit of Power
The watt (W) is the SI unit of power, defined as one joule per second. It measures the rate of energy conversion or transfer. Named after Scottish inventor James Watt, the unit is fundamental to electrical and mechanical engineering. A 60 W light bulb consumes 60 joules of electrical energy every second. A human climbing stairs might output about 200 W. The watt is small enough for most consumer electronics but large enough for scientific calculations. To convert watts to kilowatts, divide by 1000. To convert watts to horsepower, divide by 745.7.
Kilowatts (kW) - Everyday Appliances and Electric Vehicles
One kilowatt (kW) equals 1,000 watts. This is the most common unit for household appliances, electric motors, and solar panel ratings. A typical microwave oven uses 1‑1.5 kW, an electric kettle about 2‑3 kW, and a clothes dryer 3‑5 kW. Electric car motors are rated in kW - a Tesla Model 3 has about 200‑300 kW. Utility bills charge for energy in kilowatt‑hours (kWh), not power, but the kW rating determines peak demand. To convert kW to watts, multiply by 1,000. To convert kW to hp, multiply by 1.34102.
Megawatts (MW) and Gigawatts (GW) - Power Plants and Grids
One megawatt (MW) = 1,000 kW = 1,000,000 W. One gigawatt (GW) = 1,000 MW = 1,000,000 kW = 10⁹ W. These units are used for large‑scale power generation. A typical coal or nuclear power plant produces 500‑1,500 MW. The largest wind turbines generate 10‑15 MW each. The total electricity consumption of the United States is about 1,000 GW (1 TW) peak. To convert MW to kW, multiply by 1,000. To convert GW to MW, multiply by 1,000.
Horsepower (hp) - Engines and Motors
Horsepower (hp) is a traditional unit of power, originally defined by James Watt to compare steam engines to draft horses. One mechanical horsepower equals exactly 745.699872 watts. Different types of horsepower exist (metric hp ≈ 735.5 W, electric hp = 746 W), but mechanical hp is the most common in automotive and industrial contexts. A modern family car has 150‑250 hp; a supercar might have 600‑1,000 hp. To convert horsepower to kilowatts, multiply by 0.7457. To convert kW to hp, multiply by 1.341. Our converter uses the standard mechanical horsepower.
BTU per second (BTU/s) - Thermal Power
The British Thermal Unit (BTU) is a unit of energy; BTU per second (BTU/s) is a unit of power. One BTU is about 1,055 joules. BTU/s is used for high‑power heating systems, industrial furnaces, and sometimes for gas appliances. More commonly, HVAC systems use BTU per hour (BTU/hr). Our converter includes BTU/s for thermal power calculations. To convert BTU/s to watts, multiply by 1,055.05585.
Ton of Refrigeration (TR) - Cooling Capacity
The ton of refrigeration (TR) is a unit of cooling power, defined as the rate of heat absorption needed to freeze one short ton (2,000 lb) of water at 32°F in 24 hours. One TR equals 12,000 BTU per hour, or approximately 3.517 kW (3,516.85 W). It is the standard unit for air conditioning and refrigeration capacity worldwide. A residential AC unit might be 2‑5 TR, a commercial chiller 50‑500 TR. To convert tons of refrigeration to kilowatts, multiply by 3.51685. To convert kW to TR, divide by 3.51685.
Common Power Conversions - Quick Reference Formulas
Metric ↔ Metric
- kW → W: multiply by 1,000
- MW → kW: multiply by 1,000
- GW → MW: multiply by 1,000
- W → kW: divide by 1,000
- kW → MW: divide by 1,000
- MW → GW: divide by 1,000
Metric ↔ Horsepower
- kW → hp: multiply by 1.34102
- hp → kW: multiply by 0.7457
- W → hp: divide by 745.7
- hp → W: multiply by 745.7
Metric ↔ BTU/s
- W → BTU/s: divide by 1055.05585
- BTU/s → W: multiply by 1055.05585
- kW → BTU/s: multiply by 0.947817
Refrigeration Tons
- TR → kW: multiply by 3.51685
- kW → TR: divide by 3.51685
- TR → BTU/s: multiply by 3.33333 (since 1 TR = 12,000 BTU/hr = 3.3333 BTU/s)
- TR → hp: multiply by 4.716 (approx)
Real-World Applications of Power Conversion
Understanding how to convert between power units is essential across many fields. Here are real-world scenarios where our watt conversion calculator proves invaluable:
Automotive Performance Comparisons
Car enthusiasts often compare engines rated in horsepower (US) vs. kilowatts (Europe). A European specification sheet might list 150 kW; a US buyer needs to know that equals about 201 hp. Our kW to hp converter gives the answer instantly.
Generator Sizing for Homes and Events
Portable generators are rated in watts or kilowatts, but appliance power ratings vary. A refrigerator might draw 600 W, a sump pump 1,500 W, and a window AC unit 1,200 W. Adding these up tells you the minimum generator size in kW. Our converter helps consolidate units.
HVAC System Design
Air conditioners and heat pumps are rated in tons of refrigeration (TR) in North America, but in kW in most other countries. An HVAC engineer specifying a 10 TR chiller needs to convert to kW (35.17 kW) for compressor power calculations. Our tool handles TR ↔ kW seamlessly.
Renewable Energy and Power Plants
Solar farms and wind turbines are rated in MW or GW. Converting between MW and GW helps compare projects of different scales. A 500 MW solar farm is 0.5 GW. Our converter is used by energy analysts daily.
Frequently Asked Questions (FAQ) About Power Conversion
How do I convert watts to horsepower?
To convert watts to horsepower (hp), divide the watt value by 745.7. For example, 1,000 W ÷ 745.7 = 1.341 hp. Conversely, to convert hp to watts, multiply by 745.7. Our tool does this instantly.
How many BTUs per second are in a kilowatt?
One kilowatt (kW) equals approximately 0.9478 BTU per second. The exact conversion factor is 1 kW = 0.947817 BTU/s. To convert kW to BTU/s, multiply by 0.9478.
What is a ton of refrigeration in watts?
One ton of refrigeration (TR) equals exactly 12,000 BTU per hour. Since 1 BTU/hr ≈ 0.293071 W, 1 TR = 12,000 × 0.293071 = 3,516.85 W (3.51685 kW). Our converter includes this precise value.
How accurate is this power converter?
Our converter uses internationally recognized exact conversion factors (e.g., 1 hp = 745.699872 W). Results are displayed to 6 decimal places, providing accuracy suitable for engineering, education, and professional use.
Can I use this power unit converter offline?
Yes. Once the page has loaded, all conversion logic runs locally in your browser. No internet connection is required after initial load, making it perfect for field work or areas with poor connectivity.
What is the difference between metric horsepower and mechanical horsepower?
Mechanical horsepower (used in our converter) is defined as 745.699872 W. Metric horsepower (used in some European contexts) is defined as 735.49875 W (75 kgf·m/s). Our tool uses mechanical horsepower, which is standard for automotive and industrial applications in the US and most engineering contexts.
Why Choose Our Power Converter Over Others?
- Completely free, no registration. Unlimited power conversions with no hidden costs.
- Privacy‑first design. All calculations happen locally in your browser. Your data never leaves your device.
- Supports 8 power units - including rare but essential units like tons of refrigeration and BTU/s.
- High precision with results to 6 decimal places, suitable for engineering and scientific work.
- User‑friendly features including unit swap, fullscreen mode, one‑click copy, and local save of recent selections.
- Works offline after initial page load.
- Fully responsive design with resizable panels on desktop.
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