Power Converter
Convert between units of power including watts, kilowatts, horsepower, BTU per hour, and calories per second. Essential for engineering, physics, and various technical applications.
Convert Power Units
Enter a power value and select the units to convert between:
1 kW = 1,000 W β’ 1 hp (mechanical) β 746 W β’ 1 BTU/h β 0.293 W
Understanding Power Units
Power is the rate of energy transfer or work done per unit time. Different industries use different units depending on their applications and historical conventions.
Power Unit Systems
β‘ SI Units (International System)
Watt (W): Base unit of power
Kilowatt (kW): 1,000 W
Megawatt (MW): 1,000,000 W
Joule/second (J/s): Same as watt
Used in science and modern engineering
π Horsepower
Metric: 735.5 W (European standard)
Mechanical: 745.7 W (US standard)
Based on horse-drawn work
Difference: ~1.36%
Used in automotive and mechanical engineering
π₯ Thermal Units
BTU/hour: British Thermal Unit per hour
Calorie/second: Heat energy transfer
Kilocalorie/hour: Nutrition and heating
Used in HVAC and thermodynamics
Relates directly to heat transfer
Complete Power Conversion Table
| Unit | Symbol | Watts | Description |
|---|---|---|---|
| Watt | W | 1 | SI base unit of power |
| Kilowatt | kW | 1,000 | Common for appliances and small generators |
| Megawatt | MW | 1,000,000 | Power plants and large industrial systems |
| Horsepower (metric) | hp | 735.5 | European standard, exactly 75 kgfΒ·m/s |
| Horsepower (mechanical) | hp | 745.7 | US standard, 550 ftΒ·lbf/s |
| BTU per hour | BTU/h | 0.293 | Heating and cooling capacity |
| Calorie per second | cal/s | 4.184 | Heat transfer rate |
| Kilocalorie per hour | kcal/h | 1.163 | Nutrition and small heating systems |
| Foot-pound per second | ftΒ·lbf/s | 1.356 | US customary mechanical power |
Common Power Ratings
| Device/Application | Typical Power | Description |
|---|---|---|
| Incandescent Light Bulb | 60 W | Traditional household bulb |
| LED Light Bulb | 10 W | Energy-efficient replacement |
| Microwave Oven | 1,000 W | Kitchen appliance peak power |
| Electric Car Motor | 100 kW | Tesla Model 3 performance motor |
| Air Conditioner | 12,000 BTU/h | Window unit cooling capacity |
| Gasoline Engine | 200 hp | Sports car performance |
| Nuclear Power Plant | 1,000 MW | Large reactor output |
| Human Metabolism | 100 W | Average resting power output |
Horsepower: Metric vs Mechanical
πͺπΊ Metric Horsepower (hpM)
Defined as: 75 kgfΒ·m/s
Exactly 735.49875 watts
Used in Europe and scientific contexts
Based on gravitational force
More precise definition
πΊπΈ Mechanical Horsepower (hpI)
Defined as: 550 ftΒ·lbf/s
Approximately 745.7 watts
Used in United States and automotive
Based on foot-pounds of work
Traditional US engineering standard
π Key Difference
Mechanical horsepower is 1.36% higher
This can affect engine ratings significantly
Always specify which system you're using
Important for international specifications
Modern engines often use both systems
Electrical vs Mechanical Power
β‘ Electrical Power
P = V Γ I (watts = volts Γ amps)
True power in AC systems
Power factor considerations
Appliance ratings
Circuit breaker sizing
π Mechanical Power
P = Ο Γ Ο (power = torque Γ angular velocity)
Engine output power
Motor shaft power
Transmission losses
Efficiency calculations
π₯ Thermal Power
Heat transfer rate
BTU and calorie measurements
HVAC system capacity
Refrigeration ratings
Combustion engine heat
Power in Different Industries
ποΈ Engineering
Motor power ratings
Pump specifications
Generator capacity
Transmission efficiency
System design calculations
π Home Appliances
Light bulb wattage
Microwave power
Electric stove ratings
Water heater capacity
Energy consumption monitoring
π Automotive
Engine horsepower
Electric motor power
Hybrid system ratings
Fuel efficiency calculations
Performance specifications
Power and Energy Relationship
β‘ Power Definition
Power = Energy / Time
Rate of energy transfer
Work done per unit time
SI unit: joule/second = watt
Fundamental physical quantity
π Energy Calculation
Energy = Power Γ Time
Kilowatt-hours for electricity bills
BTU for heating calculations
Calorie content in nutrition
Work = Force Γ Distance
β±οΈ Time Factor
Power Γ time = energy
Hourly rates vs instantaneous power
Average vs peak power
Duty cycles and efficiency
Cost calculations
β‘ Power Tip: Remember that power is the rate of energy transfer. A 100-watt light bulb uses 100 joules of energy every second. Horsepower ratings differ between metric (735 W) and mechanical (746 W) systems - always check which standard is being used.