Power Unit Converter

Convert between all power units instantly. Our comprehensive power converter handles watts, kilowatts, horsepower, BTU per hour, and all common power measurements for appliances, engines, HVAC systems, and industrial equipment.

Quick Power Conversions

Most Popular Power Conversions

• Watts to Kilowatts → - Appliance power ratings
• Horsepower to Watts → - Engine specifications
• Kilowatts to Horsepower → - Electric motor ratings
• BTU/h to Watts → - HVAC capacity
• Watts to BTU/h → - Air conditioner specs

By Application

Home Appliances:

• Watts to Kilowatts → - Typical household appliances: 100W-3000W (0.1-3 kW)
• Kilowatts to Megawatts → - Large equipment

Automotive & Engines:

• Horsepower to Kilowatts → - Car engines: 100-500 hp (75-373 kW)
• Horsepower to Watts → - Small engines and motors
• Metric Horsepower to Horsepower → - European vs US specs

HVAC & Heating:

• BTU/h to Kilowatts → - Air conditioner capacity
• Tons of Refrigeration to Kilowatts → - Commercial HVAC
• Kilowatts to BTU/h → - Heating capacity

Industrial & Scientific:

• Megawatts to Gigawatts → - Power plants
• Joules per Second to Watts → - SI fundamental units

Understanding Power Units

What is Power?

Power measures the rate at which work is done or energy is transferred. It tells you how much energy is used or produced per unit of time.

Key Formula: Power = Energy ÷ Time

Example: A 100-watt light bulb uses 100 joules of energy every second.

Common Power Units Explained

Watt (W)

SI unit of power. 1 watt = 1 joule per second.

Common Uses:

• Light bulbs: 5W (LED) to 100W (incandescent)
• Laptop chargers: 45W to 90W
• Phone chargers: 5W to 20W
• Microwave ovens: 600W to 1200W

Convert Watts →

Kilowatt (kW)

1,000 watts. Standard unit for household appliances and small industrial equipment.

Common Uses:

• Electric vehicles: 50-300 kW
• Home heating: 10-20 kW
• Air conditioners: 2-5 kW
• Electric stoves: 2-3 kW per burner

Electricity Bills: Your utility charges per kilowatt-hour (kWh), which is energy, not power. A 1 kW appliance running for 1 hour uses 1 kWh of energy.

Convert Kilowatts →

Horsepower (hp)

Imperial/US unit. Originally defined as the power of a draft horse.

Types:

• Mechanical horsepower (hp): 745.7 watts (US standard)
• Metric horsepower (PS): 735.5 watts (European standard)
• Electric horsepower: 746 watts (electric motors)

Common Uses:

• Car engines: 100-500 hp
• Lawnmowers: 3-7 hp
• Industrial motors: 1-1000+ hp
• Vacuum cleaners: 1-2 hp

Convert Horsepower →

BTU per Hour (BTU/h)

British Thermal Units per hour. Common in North American HVAC industry.

Common Uses:

• Air conditioners: 5,000-24,000 BTU/h (residential)
• Furnaces: 40,000-100,000 BTU/h
• Water heaters: 30,000-50,000 BTU/h
• Space heaters: 10,000-30,000 BTU/h

Quick conversion: 3,412 BTU/h = 1 kW

Convert BTU/h →

Ton of Refrigeration (TR)

Cooling power unit. 1 TR = 12,000 BTU/h = 3.517 kW

Originally defined as the rate of heat removal needed to freeze one ton of water in 24 hours.

Common Uses:

• Residential AC: 1.5-5 tons
• Commercial AC: 10-100+ tons
• Industrial chillers: 100-1000+ tons

Example: A 3-ton AC unit can remove 36,000 BTU/h of heat.

Convert Tons of Refrigeration →

Power by Application

Home Appliances Power Ratings

Appliance	Typical Power	Annual Energy Cost*
LED light bulb	8-12W	$1-2
Incandescent bulb	60-100W	$8-12
Phone charger	5-20W	$1-3
Laptop	45-90W	$10-20
Desktop computer	200-500W	$40-100
LCD TV (50")	100-150W	$20-30
Refrigerator	100-800W	$50-150
Microwave	600-1200W	$20-40
Dishwasher	1200-1500W	$35-50
Washing machine	500-2000W	$40-80
Electric dryer	2000-5000W	$100-200
Electric oven	2000-5000W	$60-120
Air conditioner (window)	1000-1500W	$100-200
Central AC (3-ton)	3000-5000W	$300-600
Electric water heater	3000-4500W	$300-500
Hair dryer	1500-1875W	$5-10

*Based on typical usage and $0.15/kWh electricity rate

Calculate your energy costs →

Automotive Engine Power

Vehicle Type	Power (hp)	Power (kW)
Small car (economy)	75-110 hp	55-82 kW
Midsize sedan	150-200 hp	112-149 kW
SUV	200-300 hp	149-224 kW
Sports car	300-500 hp	224-373 kW
Supercar	500-1000+ hp	373-746+ kW
Truck (light-duty)	200-400 hp	149-298 kW
Semi-truck	400-600 hp	298-447 kW
Motorcycle	50-200 hp	37-149 kW
Electric vehicle	100-1000+ hp	75-746+ kW
Hybrid vehicle	100-300 hp	75-224 kW

Convert engine specs: HP to kW →

HVAC System Capacity

Application	Power Range	BTU/h Range
Window AC (small room)	0.4-1.0 kW	1,400-3,400 BTU/h
Window AC (large room)	1.0-2.0 kW	3,400-7,000 BTU/h
Central AC (1500 sq ft)	3.5-5.3 kW	12,000-18,000 BTU/h
Central AC (2500 sq ft)	7.0-10.5 kW	24,000-36,000 BTU/h
Commercial rooftop unit	10.5-35 kW	36,000-120,000 BTU/h
Space heater (portable)	1.5 kW	5,000 BTU/h
Gas furnace (residential)	15-30 kW	50,000-100,000 BTU/h
Electric furnace	10-20 kW	34,000-68,000 BTU/h
Heat pump	3.5-10.5 kW	12,000-36,000 BTU/h

Size your HVAC: BTU/h to kW →

Industrial & Power Generation

System	Typical Power	Context
Solar panel (residential)	250-400W	Per panel
Residential solar array	5-10 kW	Whole house system
Wind turbine (small)	1-10 kW	Off-grid applications
Wind turbine (utility)	2-5 MW	Onshore wind farms
Wind turbine (offshore)	8-15 MW	Latest offshore turbines
Diesel generator (portable)	2-10 kW	Backup power
Standby generator	10-50 kW	Whole house backup
Industrial generator	100 kW-10 MW	Facilities, data centers
Gas turbine	1-500 MW	Power plants
Coal power plant	500-1500 MW	Base load generation
Nuclear reactor	1000-1600 MW	Base load generation
Hydroelectric dam	100-22,500 MW	Renewable base load

Convert industrial power: MW to GW →

Real-World Examples

Example 1: Air Conditioner Sizing

Question: You need to cool a 1,800 sq ft house in a hot climate. The recommended cooling is 25 BTU/h per square foot. What size AC do you need?

Calculation:

• Required cooling: 1,800 sq ft × 25 BTU/h = 45,000 BTU/h
• In tons: 45,000 BTU/h ÷ 12,000 = 3.75 tons
• In kilowatts: 45,000 BTU/h ÷ 3,412 = 13.2 kW

Answer: You need a 4-ton (48,000 BTU/h or 14.1 kW) central air conditioning system.

Calculate AC capacity: BTU/h to Tons →

Example 2: Electric Vehicle Power

Question: A Tesla Model 3 Performance has 450 hp. How does this compare in kilowatts?

Calculation:

• 450 hp × 0.7457 = 335.6 kW

Context: This is peak power output. At highway speeds (75 mph), the car might only use 20-30 kW to maintain speed, but has the full 335 kW available for acceleration.

Convert EV specs: HP to kW →

Example 3: Home Energy Usage

Question: Your home uses the following appliances simultaneously. What's your total power draw?

• Central AC: 3500W
• Refrigerator: 150W
• TV: 120W
• 10 LED bulbs: 10W each
• Laptop: 65W

Calculation:

• Total: 3500 + 150 + 120 + (10×10) + 65 = 3935W = 3.935 kW

Cost per hour: 3.935 kW × $0.15/kWh = $0.59/hour

If you run this 8 hours/day for a month:

• Daily cost: $0.59 × 8 = $4.72
• Monthly cost: $4.72 × 30 = $141.60

Calculate electricity costs →

Example 4: Generator Sizing

Question: You want a backup generator for essential loads:

• Refrigerator: 800W (startup surge: 2400W)
• Sump pump: 800W (startup surge: 1300W)
• Furnace blower: 600W
• Lights: 300W
• Internet/security: 100W

Calculation:

• Running watts: 800 + 800 + 600 + 300 + 100 = 2,600W
• Startup surge (worst case): 2,400W (fridge) + 800 + 600 + 300 + 100 = 4,200W

Answer: You need at least a 5,000W (5 kW) generator to handle startup surges. A 7,500W generator would provide a comfortable safety margin.

Example 5: Solar Array Design

Question: Your home averages 30 kWh per day electricity usage. How much solar capacity do you need?

Calculation:

• Daily usage: 30 kWh
• Assuming 5 peak sun hours per day
• Required capacity: 30 kWh ÷ 5 hours = 6 kW

System losses (inverter, wiring, dirt, etc.): ~20%

• Adjusted capacity: 6 kW ÷ 0.8 = 7.5 kW

Number of panels (assuming 350W panels):

• Panels needed: 7,500W ÷ 350W = 21.4 → 22 panels

Answer: Install a 7.7 kW system (22 × 350W panels) to meet your daily energy needs.

Common Conversion Mistakes to Avoid

❌ Mistake #1: Confusing Power and Energy

Wrong: "My 100W light bulb uses 100W per hour"

Correct:

• Power (W) is the rate of energy use
• Energy (Wh) is power × time
• A 100W bulb uses 100 watt-hours (0.1 kWh) in 1 hour

Why it matters: Your electric bill charges for energy (kWh), not power (kW).

❌ Mistake #2: Wrong Horsepower Type

Wrong: Assuming all horsepower is the same

Correct:

• Mechanical HP (US): 745.7W
• Metric HP (PS): 735.5W
• Electric HP: 746W

Example: A European car rated at 150 PS = 110 kW = 147.5 US hp (not 150 hp)

Convert correctly: Metric HP to HP →

❌ Mistake #3: Ignoring Startup Power

Wrong: Sizing a generator only for running watts

Correct: Many motors need 2-3x their running power during startup

• Refrigerator running: 800W
• Refrigerator starting: 2,400W
• Generator must handle 2,400W surge

Fix: Always check surge/starting watts when sizing generators or circuits.

❌ Mistake #4: AC Sizing Errors

Wrong: Bigger is always better for air conditioners

Correct:

• Oversized AC units cycle too frequently
• Reduces efficiency and comfort
• Doesn't dehumidify properly

Proper sizing factors:

• Square footage
• Climate zone
• Insulation quality
• Ceiling height
• Sun exposure

Rule of thumb: 20-25 BTU/h per square foot (varies by climate)

❌ Mistake #5: Mixing Peak and Continuous Power

Wrong: Using peak power for continuous calculations

Example: A 200 hp (149 kW) car engine

• Peak power: 200 hp at 6000 RPM
• Highway cruising: ~25 hp (19 kW) at 2000 RPM

Why it matters:

• Battery sizing
• Generator runtime calculations
• Fuel consumption estimates

Use average or continuous power ratings for duration/energy calculations.

Power Conversion Formulas

Standard SI Conversions

Watts to Kilowatts:

• kW = W ÷ 1,000
• Example: 5,000W = 5 kW

Kilowatts to Megawatts:

• MW = kW ÷ 1,000
• Example: 5,000 kW = 5 MW

Horsepower Conversions

Horsepower to Watts:

• W = hp × 745.699872
• Example: 100 hp = 74,570 W = 74.57 kW

Horsepower to Kilowatts:

• kW = hp × 0.7457
• Example: 300 hp = 223.7 kW

Metric HP (PS) to Watts:

• W = PS × 735.49875
• Example: 100 PS = 73,550 W = 73.55 kW

Metric HP to Mechanical HP:

• hp = PS × 0.9863
• Example: 150 PS = 147.9 hp

BTU per Hour Conversions

BTU/h to Watts:

• W = BTU/h × 0.293071
• Example: 12,000 BTU/h = 3,517 W = 3.517 kW

BTU/h to Kilowatts:

• kW = BTU/h ÷ 3,412.14
• Example: 24,000 BTU/h = 7.03 kW

Watts to BTU/h:

• BTU/h = W × 3.412142
• Example: 1,000W = 3,412 BTU/h

Refrigeration Ton Conversions

Tons to BTU/h:

• BTU/h = tons × 12,000
• Example: 3 tons = 36,000 BTU/h

Tons to Kilowatts:

• kW = tons × 3.51685
• Example: 4 tons = 14.07 kW

BTU/h to Tons:

• tons = BTU/h ÷ 12,000
• Example: 48,000 BTU/h = 4 tons

Mechanical Conversions

Foot-pounds per second to Watts:

• W = ft⋅lb/s × 1.35582
• Example: 550 ft⋅lb/s = 745.7W = 1 hp

Calories per second to Watts:

• W = cal/s × 4.184
• Example: 100 cal/s = 418.4W

Quick Reference Table

From	To	Multiply by
Watt	Kilowatt	0.001
Kilowatt	Watt	1,000
Kilowatt	Horsepower	1.341
Horsepower	Kilowatt	0.7457
Horsepower	Watt	745.7
Metric HP (PS)	Horsepower	0.9863
BTU/h	Watt	0.2931
BTU/h	Kilowatt	0.0002931
Watt	BTU/h	3.412
Kilowatt	BTU/h	3,412
Ton (refrig.)	BTU/h	12,000
Ton (refrig.)	Kilowatt	3.517
Megawatt	Kilowatt	1,000
Gigawatt	Megawatt	1,000

Use our calculator for precise conversions →

Power FAQs

What is the difference between power and energy?

Power is the rate at which energy is used or produced (measured in watts).

Energy is the total amount of work done over time (measured in watt-hours or joules).

Analogy:

• Power is like speed (miles per hour)
• Energy is like distance (miles traveled)

Example:

• A 100W light bulb (power rating)
• Running for 10 hours
• Uses 1,000 Wh = 1 kWh (energy)

Your electricity bill charges for energy (kWh), not power (kW).

How many watts is 1 horsepower?

1 mechanical horsepower = 745.7 watts

Quick conversions:

• 1 hp = 0.7457 kW
• 1 kW = 1.341 hp
• 100 hp = 74.57 kW
• 300 hp = 223.7 kW

Types of horsepower:

• Mechanical (US): 745.7W
• Metric (PS): 735.5W
• Electric: 746W

The differences are small (1-2%) but matter for precise engineering calculations.

Convert Horsepower to Watts →

How do I convert kW to hp?

Formula: hp = kW × 1.341

Examples:

• 10 kW = 13.4 hp
• 50 kW = 67.1 hp
• 100 kW = 134.1 hp
• 200 kW = 268.2 hp

Quick mental math: Multiply kW by 1.34 (or 1.3 for rough estimates)

Use cases:

• Electric motor specifications
• Electric vehicle comparisons
• Generator ratings

Convert Kilowatts to Horsepower →

What size air conditioner do I need?

Basic calculation: 20 BTU/h per square foot (moderate climate)

Adjusted by climate:

• Cool climate: 18-20 BTU/h per sq ft
• Moderate climate: 20-25 BTU/h per sq ft
• Hot climate: 25-30 BTU/h per sq ft

Additional factors (add 10-20%):

• High ceilings (>8 feet)
• Lots of windows
• Top floor or flat roof
• Poor insulation

Example (1,500 sq ft, moderate climate):

• 1,500 sq ft × 22 BTU/h = 33,000 BTU/h
• In tons: 33,000 ÷ 12,000 = 2.75 tons
• Choose: 3-ton (36,000 BTU/h) unit

In kilowatts: 36,000 BTU/h ÷ 3,412 = 10.5 kW

Calculate AC size: BTU/h conversions →

How much power does a typical house use?

Average US household: 30 kWh per day = 1.25 kW average continuous

Peak power demand (all major appliances on):

• Typical: 5-10 kW
• All-electric home: 10-20 kW
• With EV charging: 15-30 kW

Major contributors:

• HVAC: 40-60% of usage
• Water heater: 15-20%
• Appliances: 15-20%
• Lighting: 5-10%

By season:

• Summer peak: 40-50 kWh/day (AC running)
• Winter peak: 50-60 kWh/day (electric heat)
• Mild seasons: 20-30 kWh/day

Service panel ratings:

• Small home: 100-amp service = 24 kW max
• Average home: 200-amp service = 48 kW max
• Large home: 400-amp service = 96 kW max

What is a ton of refrigeration?

1 ton of refrigeration (TR) = 12,000 BTU/h = 3.517 kW

Origin: The cooling power needed to freeze one ton (2,000 lbs) of water in 24 hours.

Common AC sizes:

• 1.5 tons = 18,000 BTU/h - Small apartment
• 2 tons = 24,000 BTU/h - Small house
• 3 tons = 36,000 BTU/h - Medium house (1,500 sq ft)
• 4 tons = 48,000 BTU/h - Large house (2,000 sq ft)
• 5 tons = 60,000 BTU/h - Very large house (2,500+ sq ft)

Not related to weight: Despite the name, this has nothing to do with how much the AC unit weighs.

Convert Tons to kW or BTU/h →

How many watts does it take to run a house?

Average continuous power: 1,000-2,000W (1-2 kW)

Peak instantaneous power:

• Small home: 5,000-10,000W (5-10 kW)
• Average home: 10,000-20,000W (10-20 kW)
• Large home: 20,000-40,000W (20-40 kW)

Essential loads only (for backup generator sizing):

• Refrigerator: 800W
• Furnace/AC: 2,000-5,000W
• Lights: 500W
• Well pump: 1,000W
• Sump pump: 800W
• Total: 5,000-10,000W needed

Daily energy usage:

• Average: 30 kWh/day
• Efficient home: 15-20 kWh/day
• Large/inefficient: 50+ kWh/day

Cost: At $0.15/kWh, continuous 1.25 kW = $164/month

What's the difference between kW and kWh?

kW (kilowatt) = Power = Rate of energy use

• How fast you're using energy RIGHT NOW
• Like speed (miles per hour)

kWh (kilowatt-hour) = Energy = Total amount used

• How much energy you used over time
• Like distance (miles traveled)

Example:

• A 2 kW space heater (power rating)
• Running for 5 hours
• Uses 2 kW × 5 h = 10 kWh (energy)

Your electric bill:

• Charges per kWh (energy)
• Average US rate: $0.13-0.15 per kWh
• 10 kWh costs $1.30-1.50

Calculation: kWh = kW × hours

Calculate energy costs →

How much power is 200 horsepower in kW?

200 hp = 149.1 kW

Calculation: 200 hp × 0.7457 = 149.14 kW

Context:

• Midsize sedan engine (Honda Accord, Toyota Camry)
• Small SUV
• Moderate sports car
• Industrial motor

Comparison:

• 200 hp = 149 kW
• Enough to power ~50 typical houses (3 kW average each)
• Or charge ~25 electric vehicles simultaneously (6 kW chargers)

For other HP values:

• 100 hp = 74.6 kW
• 150 hp = 111.9 kW
• 250 hp = 186.4 kW
• 300 hp = 223.7 kW
• 400 hp = 298.3 kW

Convert your engine specs: HP to kW →

Related Conversions

• Energy Converter → - Convert kWh, BTU, joules, calories
• Fuel Consumption Converter → - MPG, L/100km calculations
• Force Converter → - Newtons, pounds-force, dynes (coming soon)
• Torque Converter → - lb-ft, N⋅m (coming soon)
• Electrical Converter → - Voltage, current, resistance (coming soon)

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