In the RF world, there are multiple uses of a variety of specifications in various forms where the units are in decibels of some type. It can be confusing by itself and then often when talking about power output, those in the know will switch from decibels to watts. This brief article strives to help you understand the ins and outs of decibels and watts.
dBW (Decibel-Watt)
- dBW definition
dBW or decibel-watt is a unit of power in decibel scale, referenced to 1 watt (W).
The power in decibel-watts (P(dBW)) is equal to 10 times base 10 logarithm of the power in watts (P(W)):
P(dBW) = 10 ⋅ log10( P(W) / 1W)
The power in watts (P(W)) is equal to 10 raised by the power in decibel-watts (P(dBW)) divided by 10:
P(W) = 1W ⋅ 10(P(dBW)/ 10)
1 watt is equal to 0 dBW:
1W = 0dBW
1 milliwatt is equal to -30dBW:
1mW = 0.001W = -30dBW
How to Convert dBW to dBm (dB milliwatts)
The power in dBm is equal to the base 10 logarithm of the power in watts (W):
P(dBm) = P(dBW) + 30
Example
What is the power in dBm for power consumption of 20dBW? Solution:
P(dBm) = 20dBW + 30 = 50dBm
dB to Watts Conversion Table
Power (dBW) | Power (dBm) | Power (Watt) |
---|---|---|
-130 dBW | -100 dBm | 0.1 pW |
-120 dBW | -90 dBm | 1 pW |
-110 dBW | -80 dBm | 10 pW |
-100 dBW | -70 dBm | 100 pW |
-90 dBW | -60 dBm | 1 nW |
-80 dBW | -50 dBm | 10 nW |
-70 dBW | -40 dBm | 100 nW |
-60 dBW | -30 dBm | 1 μW |
-50 dBW | -20 dBm | 10 μW |
-40 dBW | -10 dBm | 100 μW |
-30 dBW | 0 dBm | 1 mW |
-20 dBW | 10 dBm | 10 mW |
-10 dBW | 20 dBm | 100 mW |
-1 dBW | 29 dBm | 0.794328 W |
0 dBW | 30 dBm | 1.000000 W |
1 dBW | 31 dBm | 1.258925 W |
10 dBW | 40 dBm | 10 W |
20 dBW | 50 dBm | 100 W |
30 dBW | 60 dBm | 1 kW |
40 dBW | 70 dBm | 10 kW |
50 dBW | 80 dBm | 100 kW |
60 dBW | 90 dBm | 1 MW |
70 dBW | 100 dBm | 10 MW |
80 dBW | 110 dBm | 100 MW |
90 dBW | 120 dBm | 1 GW |
100 dBW | 130 dBm | 10 GW |