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Watt (W)

Watt definition

Watt is the unit of power (symbol: W).

The watt unit is named after James Watt, the inventor of the steam engine.

One watt is defined as the energy consumption rate of one joule per second.

1W = 1J / 1s

One watt is also defined as the current flow of one ampere with voltage of one volt.

1W = 1V × 1A

Watt to mW, kW, MW, GW, dBm, dBW conversion calculator

Convert watt to milliwatt, kilowatt, megawatt, gigawatt, dBm, dBW.

Enter the power in one of the text boxes and press the Convert button:

           
  Enter milliwatts: mW  
  Enter watts: W  
  Enter kilowatts: kW  
  Enter megawatts: MW  
  Enter gigawatts: GW  
  Enter dBm: dBm  
  Enter dBW: dBW  
         
           

Table of unit prefixes of watt

name symbol conversion example
picowatt pW 1pW  = 10-12 W P = 10 pW
nanowatt nW 1nW  = 10-9 W P = 10 nW
microwatt μW 1μW  = 10-6 W P = 10 μW
milliwatt mW 1mW = 10-3 W P = 10 mW
watt W

-

 P = 10 W
kilowatt kW 1kW   = 103 W P = 2 kW
megawatt MW 1MW  = 106 W P = 5 MW
gigawatt GW 1GW  = 109 W P = 5 GW

How to convert watts to kilowatts

The power P in kilowatts (kW) is equal to the power P in watts (W) divided by 1000:

P(kW) = P(W) / 1000

How to convert watts to milliwatts

The power P in milliwatts (mW) is equal to the power P in watts (W) times 1000:

P(mW) = P(W) · 1000

How to convert watts to dBm

The power P in decibel-milliwatts (dBm) is equal to 10 times base 10 logarithm of the power P in milliwatts (mW) divided by 1 milliwatt:

P(dBm) = 10 · log10( P(mW) / 1mW )

How to convert watts to amps

The current I in ampers (A) is equal to the power P in watts (W) divided by the voltage V in volts (V):

I(A) = P(W) / V(V)

How to convert watts to volts

The voltage V in volts (V) is equal to the power P in watts (W) divided by the current I in ampers (A):

V(V) = P(W) / I(A)

How to convert watts to ohms

R(Ω) = P(W) / I(A)2

R(Ω) = V(V)2 / P(W)

How to convert watts to btu/hr

P(BTU/hr) = 3.412142 · P(W)

How to convert watts to joules

E(J) = P(W) · t(s)

How to convert watts to horsepower

P(HP) = P(W) / 746

How to convert watts to kVA

The real power P in watts (W) is equal to 1000 times the apparent power S in kilo-volt-amperes (kVA) times the power factor (PF) or cosine of the phase angle φ:

P(W) = 1000 · S(kVA) · PF = 1000 · S(kVA) · cos φ

How to convert watts to VA

The real power P in watts (W) is equal to the apparent power S in volt-amperes (VA) times the power factor (PF) or cosine of the phase angle φ:

P(W) = S(VA) · PF = S(VA) · cos φ

Power consumption of some electrical components

How many watts does a house use? How many watts does a TV use? How many watts does a refrigerator use?

Electric component Typical power consumption in watts
LCD TV 30..300 W
LCD monitor 30..45 W
PC desktop computer 300..400 W
Laptop computer 40..60 W
Refrigerator 150..300 W (when active)
Light bulb 25..100 W
Fluorescent light 15..60 W
Halogen light 30..80 W
Speaker 10..300 W
Microwave 100..1000 W
Air conditioner 1..2 kW

 

Kilowatt (kW) ►

 

See also