Power Unit Converter - Watt, Kilowatt, Horsepower, BTU/h

Converter

Common Units

Formulas

Examples

Guide

Power Converter

Important Note: Power is the rate of energy transfer or work done per unit time. This converter handles all major power units used in electrical, mechanical, and thermal applications.

From Power

From Unit

To Power

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Common Power Units

Watt

SI unit of power. 1 W = 1 J/s. Basic unit for electrical and mechanical power.

Kilowatt

1000 watts. Common for household appliances and small motors. Used in electricity billing.

Horsepower

Traditional mechanical power unit. 1 hp ≈ 746 W. Used for engines and motors.

BTU per Hour

BTU/h

Thermal power unit. Common in HVAC systems for heating and cooling capacity.

Megawatt

1 million watts. Used for large industrial systems and power plant output.

Metric Horsepower

European horsepower standard. 1 PS ≈ 735 W. Used in automotive industry.

Power Conversion Table

Unit	Watts (W)	Horsepower (hp)	kW	BTU/h	Common Application
1 Watt	1	1.34×10⁻³	0.001	3.41	LED bulb
1 Kilowatt	1,000	1.34	1	3,412	Space heater
1 Horsepower	745.7	1	0.746	2,545	Car engine (1 hp)
1 Metric HP	735.5	0.986	0.735	2,510	European cars
1 BTU/h	0.293	3.93×10⁻⁴	2.93×10⁻⁴	1	Air conditioner
1 Megawatt	1,000,000	1,341	1,000	3.41×10⁶	Small power plant

Power Formulas & Calculations

Basic Power Formula

P = W/t

Power = Work/Time

Fundamental definition of power as rate of energy transfer.

Electrical Power (DC)

P = V × I

P = V²/R = I²R

Electrical power calculations using voltage, current, and resistance.

Mechanical Power

P = F × v

P = τ × ω

Force × velocity OR Torque × angular velocity.

AC Electrical Power

P = V × I × cos(φ)

Real Power (Watts)

AC power with power factor consideration (φ = phase angle).

Thermal Power

P = Q/t

P = ṁ × cp × ΔT

Heat transfer rate or mass flow thermal power.

Hydraulic Power

P = ρ × g × Q × H

P = Pressure × Flow Rate

Fluid power calculations for pumps and turbines.

Power Conversion Factors

From	To	Multiply by	Common Use
Horsepower	Watts	745.7	Engine ratings
kW	Horsepower	1.341	Motor specifications
BTU/h	Watts	0.2931	HVAC calculations
Watts	BTU/h	3.412	Heat load calculations
Ton Refrigeration	kW	3.517	Cooling systems
Boiler HP	kW	9.81	Steam generation

Important: Always distinguish between mechanical horsepower (745.7 W) and metric horsepower (735.5 W) when doing conversions.

Power Examples & Applications

🏠 Household Appliances

LED bulb: 8-12 W
Laptop computer: 65-90 W
Microwave oven: 700-1,200 W
Hair dryer: 1,500-1,875 W
Electric kettle: 2,000-3,000 W
Air conditioner: 2,000-5,000 W

🚗 Automotive Engines

Small car (1.0L): 60-75 hp (45-55 kW)
Compact car (1.6L): 120-140 hp (89-104 kW)
Mid-size car (2.0L): 180-220 hp (134-164 kW)
Sports car (V8): 400-500 hp (298-373 kW)
Motorcycle (600cc): 100-120 hp (75-89 kW)
Semi truck: 400-600 hp (298-447 kW)

🏭 Industrial Equipment

Small electric motor: 0.5-5 kW
Industrial compressor: 15-200 kW
Large pump: 50-500 kW
Wind turbine: 1.5-3 MW
Diesel generator: 10 kW-10 MW
Electric arc furnace: 10-100 MW

🔌 Power Generation

Solar panel (residential): 250-400 W
Small wind turbine: 1-10 kW
Large wind turbine: 2-8 MW
Coal power plant: 500-2,000 MW
Nuclear reactor: 1,000-1,600 MW
Hydroelectric dam: 50-22,500 MW

HVAC Power Examples

🏠 Residential HVAC

Window AC unit: 5,000-12,000 BTU/h (1.5-3.5 kW)

Central air system: 24,000-60,000 BTU/h (7-18 kW)

Heat pump: 18,000-36,000 BTU/h (5.3-10.6 kW)

🏢 Commercial HVAC

Small office building: 100-500 kW cooling

Shopping mall: 1-5 MW cooling

Hospital: 2-10 MW total HVAC

🔥 Heating Systems

Gas furnace: 60,000-120,000 BTU/h (18-35 kW)

Electric heater: 1,500-5,000 W

Boiler system: 100,000-1,000,000 BTU/h (29-293 kW)

Power Guide & Applications

📏 Understanding Power

Power: Rate of energy transfer (Energy/Time)
Unit: Watt (W) = Joule per second (J/s)
Not energy: Power × Time = Energy
Peak vs average: Instantaneous vs sustained power

🔌 Electrical vs Mechanical

Electrical: V×I, used for motors, appliances
Mechanical: Force×velocity, engine output
Conversion: Electric motor ~85-95% efficient
Losses: Heat, friction, electromagnetic

🌍 Power by Application

Automotive: Horsepower (hp), kW
Electrical: Watts (W), kilowatts (kW)
HVAC: BTU/h, tons of refrigeration
Industrial: Megawatts (MW), motor ratings

🎯 Practical Considerations

Safety: Circuit breaker sizing
Efficiency: Power factor in AC systems
Load calculation: Total power demand
Peak demand: Maximum power draw

⚠️ Common Mistakes

Power vs Energy: kW vs kWh confusion
HP variants: Mechanical vs metric horsepower
AC power: Forgetting power factor
Peak ratings: Nominal vs maximum power

🔄 Conversion Tips

Horsepower: 1 hp = 745.7 W (mechanical)
Metric HP: 1 PS = 735.5 W (European)
HVAC: 1 ton refrigeration = 3.517 kW
Precision: Use appropriate significant figures

Power Calculation Best Practices

Pro Tips:

Always specify which horsepower standard (mechanical vs metric)
Consider power factor for AC electrical systems
Use nameplate ratings for equipment specifications
Account for efficiency losses in power calculations
Distinguish between continuous and peak power ratings
Remember: Power = Energy ÷ Time (not the same as energy)

🔌 Power Unit Converter