# Conversion decibels to miliwatts Converting decibels to miliwatts is a crucial skill when you deal with wireless networks. In this short article I will show how to do that fast and painlessly.

The Watt is the unit in energy measurement. 1000 of Watts equal 1kW (kilowatt), 1mW what is more interesting for us equal 1/1000 mW.

The Decibel is not only uses to measure a power of the sound, but to describe how strong the radio signal is

In measuring and calculation the power of the radio signal to compare to Watt we will be using the reference point that is 1mW. We use “+” and “-” to describe if signal in dB is better or worse than a reference point, cause on the path we may have a lot of attenuation like walls, trees etc.

10dB = 10 times better signal x10
0dB = the signal is the same, no loss x1
-10dB = the signal is 10 times worse x0.1
dB in relation to 1mw looks in this way.
10dBm = 10mW
0dBm = 1mW
-10dBm – 0.1mW

As you see to compare dB in relation to miliwatts we use dBm unit decibel/miliwatt.

So, now we know +10 is 10, 0 means “the same” and -10 is 0.1.
How will we calculate the other values ? In order to calculate the other values we have to remember another important rule

3dB = 2 times better signal
-3dB = 0.5 time worse signal

3dBm = 2mW
-3dBm = 1.5mW

Now armored in this knowledge let’s try to convert some values.

Converting dBm to mW

I’ll teach you the simplest method to calculate rough value of mW

Firstly remember these 3 rules:

x+y = x*y
x-y  = x/y
x*y  = x^y

Each phrase has to contain 10 or 3 ! You have to manipulate calculations to get at the end the value of dBm but you may only use addding, substraction and multiplying. Remember also that 10 is equal 10 but 3 has to be replaced with 2

Now, let’s try to use these rules to the real values

3dBm = 2mW

10dBm = 10mW

37dBm = 10*3 + 10-3 = 10^3 + 10/2 = 1000 + 5 = 1000 * 5 =5000mw

23dBm = 10*2 + 3 = 10^2 + 2= 100 * 2 =200 mW

17dBm = 10 + (10-3) = 10 + 10/2 = 10 * 5 =50mw

26dBm = 10*2 + 3*2 = 10^2 + 2^2 = 100 + 4 = 100 * 4 =400mW 10+10

29dBm = 10*2 + 3*3 = 10^2 + 2^3 = 100 + 2^3 = 100 + 8 = 100 * 8 =800mW

28dBm = 10+ 3*6 = 10 * 2^6 = 10 * 64 = 640mW

18dBm = 3*6 = 2^6 = 64mW

8dBm = 10×2 – 3×4 = 100 – 2^4 = 100 – 16 = 100/16 = 6.25

1dBm = 10 – 3×3 = 10 – 2^3 = 10 – 8 = 10/8 = 1,25mW