Watt (W) electrical unit

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^-12W	P= 10 pW
nanowatt	nW	1nW = 10^-9W	P= 10 nW
microwatt	μW	1μW = 10^-6W	P= 10 μW
milliwatt	mW	1mW = 10^-3W	P = 10 mW
watt	W	-	P = 10 W
kilowatt	kW	1kW = 10³W	P= 2 kW
megawatt	MW	1MW = 10⁶W	P= 5 MW
gigawatt	GW	1GW = 10⁹W	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) ►

Watt (W)