dBm - dBw Watts conversion chart
- chart or table to provide a conversion between power measured in dBm or
dBW and power measured in watts. dBm and dBW are widely used in conjunction with
RF test equipment.
The decibel is widely used in radio and electronics design
calculations. When measuring radio frequency, or RF power, it is often easier to
have a measurement made in a way that it is easy to compare the two power
levels. As a result many power levels are specified in dBm or dBW, and much RF
test equipment including power meters or spectrum analysers have calibrations in
dBm or dBW. Often RF components such as mixers, oscillators and the like, as
well as the interfaces between modules in RF equipment have their levels
specified in dBm or dBW. Radio transmitters may also have their power levels
expressed in this way.
What are dBm and dBW?
In itself a decibel is not an absolute level. It is purely a comparison between
two levels, and on its own it cannot be used to measure an absolute power level.
As a result of this the quantities of dBm and dBW are used:
- dBm - This is a power expressed in decibels relative to one milliwatt.
- dBW - This is a power expressed in decibels relative to one watt.
From this it can be seen that a power level of 10 dBm is ten
dB above one milliwatt, i.e. 10 mW. Similarly a power level of 20 dBW is 100
times that of one watt, i.e. 100 watts.
A more extensive conversion table of dBm, dBW and power is
given below:
| dBm |
dBW |
Watts |
Terminology |
| +100 |
+70 |
10 000 000 |
10 Megawatts |
| +90 |
+60 |
1 000 000 |
1 Megawatt |
| +80 |
+50 |
100 000 |
100 kilowatts |
| +70 |
+40 |
10 000 |
10 kilowatts |
| +60 |
+30 |
1 000 |
1 kilowatt |
| +50 |
+20 |
100 |
100 watts |
| +40 |
+10 |
10 |
10 watts |
| +30 |
0 |
1 |
1 watt |
| +20 |
-10 |
0.1 |
100 milliwatts |
| +10 |
-20 |
0.01 |
10 milliwatts |
| 0 |
-30 |
0.001 |
1 milliwatt |
| -10 |
-40 |
0.0001 |
100 microwatts |
| -20 |
-50 |
0.00001 |
10 microwatts |
| -30 |
-60 |
0.000001 |
1 microwatt |
| -40 |
-70 |
0.0000001 |
100 nanowatts |
| -50 |
-80 |
0.00000001 |
10 nanowatts |
| -60 |
-90 |
0.000000001 |
1 nanowatt |
The use of the values dBm and dBW is widespread. They are
found as direct calibration scales on many items of RF test equipment, often
being used in preference to the more elementary basic units of watts or
milliwatts. Items of RF test equipment including power meters and RF spectrum
analyzers in particular use these units, and many RF components are also
specified in terms of power levels in dBm or dBW.
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