Power Converter
Our power converter helps you convert between 10 power units including watts, kilowatts, megawatts, horsepower, BTU/h, and more. Perfect for electrical engineering, energy calculations, and understanding power consumption. Fast, accurate, and works entirely in your browser.
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10 Power Units
Convert between watts, kilowatts, megawatts, gigawatts, horsepower, BTU/h, and more with precise calculations.
High Precision
Get accurate results with up to 6 decimal places, formatted for easy reading and professional use.
100% Private
All conversions happen in your browser. We never store or track your data.
Power Converter online
Convert between 10 power units including watts, kilowatts, megawatts, horsepower, BTU/h, and more instantly
What is Power?
Power is the rate at which energy is transferred, used, or transformed per unit of time. In the International System of Units (SI), power is measured in watts (W), named after Scottish engineer James Watt. Power represents how quickly work is done or energy is consumed. For example, a 100-watt light bulb uses energy at a rate of 100 joules per second.
Power units are essential in electrical engineering, energy systems, and everyday life. Understanding power conversion between watts, kilowatts, megawatts, horsepower, and other units is crucial for sizing electrical systems, calculating energy consumption, and comparing power generation capacities. Our converter supports 10 power units including SI metric units (milliwatt, watt, kilowatt, megawatt, gigawatt), traditional units (horsepower, metric horsepower), and specialized units (BTU per hour, foot-pound per second, calorie per second) for comprehensive power conversion needs.
According to the National Institute of Standards and Technology (NIST), the watt is the standard unit of power in the SI system. Power is fundamental to understanding electrical systems, as it directly relates to energy consumption (power × time = energy). This relationship is why utility companies bill customers in kilowatt-hours (kWh), representing the total energy consumed over time.
✗Manual Calculation
- • Time-consuming multiplication/division
- • Risk of calculation errors
- • Difficult to verify accuracy
- • No formatted output
✓Online Power Converter
- • Instant conversion results
- • High-precision calculations
- • Formatted numbers for clarity
- • Easy unit swapping
Understanding Power Units
Power units represent the rate at which energy is used or generated. Understanding each unit's origin, common applications, and relationships helps you choose the right unit for your needs and make accurate conversions. Here's a comprehensive guide to all power units supported by our converter.
SISI Metric Units
Milliwatt (mW)
Definition: One milliwatt equals 0.001 watts (1/1,000 of a watt). The prefix "milli" means one-thousandth in the metric system.
Common Uses: Milliwatts are used for very small power measurements, particularly in electronics and telecommunications. Examples include LED indicators (1-5 mW), small sensors, hearing aids, and low-power wireless devices. In laser technology, milliwatts are common for low-power lasers used in pointers, barcode scanners, and optical communication systems.
Conversion: 1 mW = 0.001 W = 0.000001 kW
Watt (W)
Definition: The watt is the base unit of power in the International System of Units (SI), named after Scottish engineer James Watt (1736-1819). One watt equals one joule per second, representing the rate of energy transfer or conversion.
History: The watt was adopted as the SI unit of power in 1960, replacing the older "horsepower" in scientific contexts. James Watt's improvements to the steam engine revolutionized the Industrial Revolution, making power measurement standardization essential.
Common Uses: Watts are used for household appliances (light bulbs: 40-100 W, laptops: 30-100 W, refrigerators: 100-400 W), small electronics, and personal devices. Most consumer electronics are rated in watts, making it the most familiar power unit for everyday use.
Conversion: 1 W = 0.001 kW = 0.000001 MW = 1 J/s
Kilowatt (kW)
Definition: One kilowatt equals 1,000 watts. The prefix "kilo" means one thousand in the metric system.
Common Uses: Kilowatts are the standard unit for household energy consumption, utility bills, and medium-scale power systems. Electric utilities bill customers in kilowatt-hours (kWh), representing energy consumed over time. Common applications include: residential solar panel systems (3-10 kW), electric vehicle charging (7-22 kW), home heating systems (5-20 kW), and small commercial buildings.
Energy Relationship: Power (kW) × Time (hours) = Energy (kWh). For example, a 2 kW heater running for 3 hours consumes 6 kWh of energy.
Conversion: 1 kW = 1,000 W = 0.001 MW = 1.341 hp
Megawatt (MW)
Definition: One megawatt equals 1,000,000 watts (1 million watts). The prefix "mega" means one million in the metric system.
Common Uses: Megawatts are used for large-scale power generation, industrial facilities, and utility-scale renewable energy. Examples include: wind turbines (1.5-8 MW each), solar farms (10-500 MW), natural gas power plants (100-1,000 MW), nuclear reactors (500-1,400 MW per unit), and large industrial facilities. One megawatt can power approximately 750-1,000 average homes.
Scale Context: A typical coal-fired power plant generates 500-1,000 MW, while a large nuclear power plant can generate 1,000-1,400 MW. Modern wind farms often have total capacities of 100-500 MW.
Conversion: 1 MW = 1,000 kW = 1,000,000 W = 1,341 hp
Gigawatt (GW)
Definition: One gigawatt equals 1,000,000,000 watts (1 billion watts). The prefix "giga" means one billion in the metric system.
Common Uses: Gigawatts are used for national and regional power generation capacity, large-scale renewable energy projects, and major power grid infrastructure. Examples include: large nuclear power plants (1-1.6 GW), massive solar installations (1-2 GW), hydroelectric dams (2-22 GW), and total national power generation capacity. The entire United States has a generating capacity of approximately 1,200 GW.
Scale Context: One gigawatt can power approximately 750,000 to 1 million average homes. The largest power plants in the world, such as China's Three Gorges Dam, generate over 22 GW. Major cities often require 1-5 GW of generating capacity.
Conversion: 1 GW = 1,000 MW = 1,000,000 kW = 1,000,000,000 W
⚙️Traditional & Imperial Units
Horsepower (hp) - Mechanical/Imperial
Definition: One mechanical horsepower equals approximately 745.7 watts. This is also called "imperial horsepower" or "mechanical horsepower" and is the standard used in the United States and United Kingdom.
History: Horsepower was originally defined by James Watt in the 18th century to compare the output of steam engines to draft horses. He determined that a horse could turn a mill wheel 2.4 times per minute, lifting 33,000 pounds one foot per minute, which equals 550 foot-pounds per second or approximately 745.7 watts.
Common Uses: Horsepower is the standard unit for rating engines, motors, and mechanical power systems. Examples include: car engines (100-700 hp), lawn mowers (5-25 hp), boats (50-1,000+ hp), industrial motors, and agricultural equipment. In the automotive industry, horsepower is the primary metric for engine performance.
Conversion: 1 hp = 745.7 W = 0.7457 kW = 1.014 PS (metric hp)
Metric Horsepower (PS) - Pferdestärke
Definition: One metric horsepower (PS, from German "Pferdestärke") equals approximately 735.5 watts. This is the standard used in most European countries and Japan.
History: Metric horsepower was defined in the 19th century as the power needed to lift 75 kilograms one meter in one second, which equals 735.49875 watts. It's slightly smaller than mechanical horsepower.
Common Uses: PS is used throughout Europe and Japan for rating car engines, motorcycles, and other vehicles. European car specifications typically list power in both kW and PS. For example, a 150 PS car engine equals approximately 110 kW or 148 hp (mechanical).
Conversion: 1 PS = 735.5 W = 0.7355 kW = 0.986 hp (mechanical)
🔧Specialized Units
BTU per Hour (BTU/h)
Definition: BTU per hour represents the rate of thermal energy transfer. One BTU (British Thermal Unit) equals the energy needed to raise one pound of water by one degree Fahrenheit. One BTU per hour equals approximately 0.293 watts.
Common Uses: BTU/h is the standard unit for heating and cooling systems in the United States. Examples include: air conditioners (5,000-24,000 BTU/h for residential), furnaces (40,000-200,000 BTU/h), heat pumps, and commercial HVAC systems. When shopping for air conditioners, you'll see ratings like "12,000 BTU" which means 12,000 BTU per hour of cooling capacity.
Practical Example: A 12,000 BTU/h air conditioner has a cooling capacity of approximately 3.5 kW. This is typically sufficient for cooling a 400-500 square foot room.
Conversion: 1 BTU/h = 0.293 W = 0.000293 kW ≈ 1/3,412 kW
Foot-Pound per Second (ft·lbf/s)
Definition: One foot-pound per second equals the power needed to apply a force of one pound-force through a distance of one foot in one second. One ft·lbf/s equals approximately 1.356 watts.
History: This unit comes from the British Imperial system and was commonly used before the adoption of horsepower and watts. It's directly related to mechanical work and power in engineering calculations.
Common Uses: Foot-pound per second is used in mechanical engineering, particularly in the United States, for calculating power in rotating machinery, torque applications, and mechanical systems. It's also used in physics education to illustrate the relationship between force, distance, and power.
Relationship: 550 ft·lbf/s = 1 horsepower (mechanical). This is the original definition of horsepower.
Conversion: 1 ft·lbf/s = 1.356 W = 0.001356 kW
Calorie per Second (cal/s)
Definition: One calorie per second equals the rate of thermal energy transfer. One calorie (thermochemical) equals 4.184 joules, so one calorie per second equals 4.184 watts.
Common Uses: Calorie per second is used in thermal engineering, nutrition science (for metabolic rates), and heat transfer calculations. It's particularly useful when working with thermal power systems, food energy, and biological processes. The human body at rest consumes energy at approximately 1-1.5 calories per second (4-6 watts), while during intense exercise, this can increase to 10-20 calories per second (40-80 watts).
Note: The "calorie" used in power calculations is the thermochemical calorie (4.184 J), not the "Calorie" (kilocalorie) used in food labeling, which is 1,000 times larger.
Conversion: 1 cal/s = 4.184 W = 0.004184 kW
Quick Reference: Power Unit Equivalents
| Unit | Watts | Kilowatts | Horsepower |
|---|---|---|---|
| 1 Milliwatt | 0.001 W | 0.000001 kW | 0.00000134 hp |
| 1 Watt | 1 W | 0.001 kW | 0.00134 hp |
| 1 Kilowatt | 1,000 W | 1 kW | 1.341 hp |
| 1 Megawatt | 1,000,000 W | 1,000 kW | 1,341 hp |
| 1 Gigawatt | 1,000,000,000 W | 1,000,000 kW | 1,341,000 hp |
| 1 Horsepower (hp) | 745.7 W | 0.7457 kW | 1 hp |
| 1 Metric Horsepower (PS) | 735.5 W | 0.7355 kW | 0.986 hp |
| 1 BTU per Hour | 0.293 W | 0.000293 kW | 0.000393 hp |
Power Conversion Impact
Understanding power units is essential for electrical engineering and energy management
Understanding Power Units
According to the National Institute of Standards and Technology (NIST), the watt is the standard SI unit of power, defined as one joule per second. Understanding power unit conversions is essential for electrical engineers, energy managers, and anyone working with electrical systems or renewable energy projects. The ability to convert between watts, kilowatts, and megawatts accurately is fundamental to proper system design and energy calculations.
Why Use Our Power Converter?
Our power converter provides instant, accurate conversions between 10 power units including watts, kilowatts, megawatts, gigawatts, horsepower (mechanical and metric), BTU per hour, and more. Whether you're working on electrical engineering projects, calculating energy consumption, comparing power generation capacities, or working with engines and motors, our tool offers the precision and ease of use you need.
Instant High-Precision Conversions
Get immediate power unit conversions with high precision (up to 6 decimal places). Perfect for electrical engineering calculations, energy system design, and professional applications. Our converter supports 10 power units including SI metric units (W, kW, MW, GW), traditional units (horsepower), and specialized units (BTU/h). All conversions use exact mathematical relationships, ensuring accurate results every time.
Easy Unit Comparison
Quickly compare power values across different units. Convert appliance wattage to kilowatts for energy bills, convert engine horsepower to kilowatts for specifications, convert solar panel capacities from kilowatts to megawatts for large installations, or convert BTU/h to watts for HVAC systems. The swap feature lets you instantly reverse conversions, making it easy to work in either direction without recalculating.
Engineering & Professional Use
Ideal for electrical engineers, mechanical engineers, energy consultants, HVAC professionals, and anyone working with power systems. Use it for sizing electrical equipment, converting engine specifications, calculating load requirements, designing renewable energy systems, HVAC system sizing, and understanding utility-scale power generation. The tool provides formatted output that's ready for professional documentation.
100% Private & Secure
All power conversions happen locally in your browser. We never store, log, or transmit your conversion values or personal information. Your calculations remain completely private, making this tool safe for sensitive engineering projects and confidential energy system designs.
Mobile-Friendly Design
Access our power converter from any device—desktop, tablet, or smartphone. The responsive design works perfectly on all screen sizes, so you can convert power units on the go. Perfect for field engineers and technicians who need quick conversions while working on-site or in the field.
Completely Free Forever
Use our power converter as much as you want, whenever you need it, without any cost. No hidden fees, no premium tiers, no usage limits. Convert power units unlimited times for free, making it perfect for students, professionals, and anyone working with electrical systems regularly.
Real-World Impact
According to the U.S. Energy Information Administration (EIA), the United States consumed approximately 4,000 terawatt-hours of electricity in 2020, equivalent to about 4,000,000,000 megawatt-hours. Understanding power unit conversions is essential for energy professionals, electrical engineers, and anyone working with renewable energy systems. Our tool helps professionals and students make accurate power calculations quickly, supporting better energy system design and more efficient electrical installations.
How It Works
Our power converter uses precise mathematical relationships between power units to provide accurate conversions instantly. Here's how the process works:
Select Units
Choose your source power unit (watt, kilowatt, or megawatt) from the "Convert From" dropdown and your target unit from the "Convert To" dropdown.
Enter Value
Type the power value you want to convert in the input field. You can enter whole numbers or decimals for precise values.
Calculate
Our system performs the precise mathematical conversion using standard SI unit relationships (1 kW = 1,000 W, 1 MW = 1,000,000 W).
View Result
Click Convert to instantly see the converted power value displayed clearly with the target unit abbreviation, formatted for easy reading.
Best Practices for Power Conversion
When converting power units, following best practices ensures accurate results and proper understanding of electrical and mechanical systems. Here are essential tips for using power converters effectively:
1. Understand the Relationship Between Units
Remember that power conversions follow standard metric prefixes: 1 kilowatt = 1,000 watts, 1 megawatt = 1,000,000 watts, and 1 gigawatt = 1,000,000,000 watts. These are exact conversions based on the International System of Units (SI). For traditional units, 1 mechanical horsepower (hp) ≈ 745.7 watts, 1 metric horsepower (PS) ≈ 735.5 watts, and 1 BTU/hour ≈ 0.293 watts. Understanding these relationships helps verify calculator results and catch potential errors in manual calculations.
2. Distinguish Between Power and Energy
Power (watts, kilowatts, megawatts) represents the rate of energy use, while energy (watt-hours, kilowatt-hours, megawatt-hours) represents total consumption over time. When calculating energy bills, multiply power by time: Power (kW) × Time (hours) = Energy (kWh). Our converter handles power units only; for energy conversions, use a dedicated energy converter.
3. Use Appropriate Precision
For most practical applications, 2-4 decimal places are sufficient. However, for precise engineering calculations, our converter provides up to 6 decimal places. Match the precision to your application: household appliances typically don't need high precision, while electrical engineering calculations may require greater accuracy.
4. Verify Results for Critical Applications
For critical engineering projects, electrical system design, or safety-related calculations, always verify results using multiple methods or professional engineering software. While our converter uses precise calculations, independent verification is essential for high-stakes applications where errors could have serious consequences.
5. Consider Context and Application
Different applications use different power units. Household appliances are typically rated in watts, utility bills show consumption in kilowatts, power plants generate electricity in megawatts or gigawatts, engines and motors are rated in horsepower, and HVAC systems use BTU per hour. Understanding which unit is appropriate for your context helps ensure clear communication and proper system understanding. Our converter supports all these common units, making it versatile for various professional applications.
Frequently Asked Questions
How do I convert power units online?
To convert power units online, select your source unit (watt, kilowatt, or megawatt) from the 'Convert From' dropdown, choose your target unit from the 'Convert To' dropdown, enter the power value you want to convert, and click the Convert button. The tool will instantly display the converted power value with high precision.
What power units are supported?
Our converter supports 10 power units: SI metric units (milliwatt, watt, kilowatt, megawatt, gigawatt), traditional units (mechanical horsepower, metric horsepower/PS), and specialized units (BTU per hour, foot-pound per second, calorie per second). Watt (W) is the basic SI unit. One kilowatt equals 1,000 watts, one megawatt equals 1,000,000 watts, and one gigawatt equals 1,000,000,000 watts. One mechanical horsepower equals approximately 745.7 watts.
Is this power converter accurate?
Yes, our power converter uses precise mathematical conversions based on the standard SI unit relationships. One kilowatt equals exactly 1,000 watts, and one megawatt equals exactly 1,000,000 watts. The tool provides results with up to 6 decimal places for accuracy and displays formatted numbers for easy reading.
Can I use this converter for electrical engineering calculations?
Yes, this tool is suitable for basic power unit conversions needed in electrical engineering, energy calculations, and power system analysis. However, for complex engineering projects, always verify calculations with professional engineering software and consult relevant standards and codes. Our converter handles the fundamental unit conversions accurately.
What are common use cases for power conversion?
Power conversion is commonly used for: calculating energy consumption (converting appliance wattage to kilowatts), sizing solar panel systems (converting total watts to kilowatts or megawatts), comparing power plant capacities (converting megawatts to gigawatts), converting engine horsepower to kilowatts for specifications, HVAC system sizing (converting BTU/h to watts or kilowatts), understanding electrical bills, and various engineering and technical applications in electrical, mechanical, and energy systems.
Is this power converter free to use?
Yes, our power converter is completely free to use. There are no registration requirements, no hidden fees, and no limits on the number of conversions you can perform. Simply enter your power values and convert between any of our 10 supported power units (watts, kilowatts, megawatts, gigawatts, horsepower, BTU/h, and more) instantly without any cost.
How do I convert kilowatts to watts?
To convert kilowatts to watts, multiply the kilowatt value by 1,000. For example, 5 kilowatts equals 5,000 watts. Our converter handles this automatically—just select 'kilowatt' as the source unit, 'watt' as the target unit, enter the value, and click Convert. The result will show the equivalent wattage.
What is the relationship between power and energy?
Power is the rate at which energy is used or generated, measured in watts. Energy is the total amount of work done or electricity consumed, measured in watt-hours or kilowatt-hours (kWh). For example, a 1,000-watt (1 kW) appliance running for 1 hour consumes 1 kWh of energy. Power units (W, kW, MW) describe the capacity or rate, while energy units (Wh, kWh, MWh) describe the total consumption over time.
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