Here is a conversion table from dBm (dB milliWatt) to Watt. dBm is used to measure the power, and is also capable to express both very large and very small values. An 3dB increase in level is equivalent to doubling the power.


How to calculate the dBm value:
\displaystyle \chi = 10 log_{10} \frac{P}{1mW}
How to calculate the milliWatt value:
\displaystyle P = 1mW \cdot 10^{\frac{\chi}{10}}

Where:
X = Power in dBm
P = Power in milliWatt

dBm Watt dBm Watt dBm Watt dBm Watt
0 1.0 mW 10 10 mW 20 100 mW 30 1.0 W
1 1.3 mW 11 13 mW 21 130 mW 31 1.3 W
2 1.6 mW 12 16 mW 22 160 mW 32 1.6 W
3 2.0 mW 13 20 mW 23 200 mW 33 2.0 W
4 2.5 mW 14 25 mW 24 250 mW 34 2.5 W
5 3.2 mW 15 32 mW 25 320 mW 35 3.2 W
6 4.0 mW 16 40 mW 26 400 mW 36 4.0 W
7 5.0 mW 17 50 mW 27 500 mW 37 5.0 W
8 6.0 mW 18 60 mW 28 600 mW 38 6.0 W
9 8.0 mW 19 80 mW 29 800 mW 39 8.0 W

How to calculate (V)SWR

\displaystyle \Gamma = \frac{V_{r}}{V_{f}}
\displaystyle \rho = \left | \Gamma  \right |
\displaystyle VSWR = \frac{V_{max}}{V_{min}} = \frac{1 + \rho}{1 - \rho}


[CP_CALCULATED_FIELDS id=”7″]

* ERP = Percentage of Effective Radiated Power

SWR Power Loss ERP*, Output to antenna
1.0:1 0.0 % 100 %
1.1:1 0.2 % 99.8 %
1.2:1 0.8 % 99.2 %
1.3:1 1.7 % 98.3 %
1.4:1 2.8 % 97.2 %
1.5:1 4.0 % 96.0 %
1.6:1 5.3 % 94.7 %
1.7:1 6.7 % 93.3 %
1.8:1 8.2 % 91.8 %
2.0:1 11.1 % 88.9 %
2.5:1 18.4 % 81.6 %
3.0:1 25.0 % 75.0 %
4.0:1 36.0 % 64.0 %
5.0:1 44.4 % 55.6 %
6.0:1 51.0 % 49.0 %
8.0:1 60.5 % 39.5 %
10.0:1 66.9 % 33.1 %
12.0:1 71.6 % 28.4 %
14.0:1 75.1 % 24.9 %
16.0:1 77.9 % 22.1 %
20.0:1 81.9 % 18.1 %
25.0:1 85.2 % 14.8 %
30.0:1 87.5 % 12.5 %
40.0:1 90.5 % 8.5 %
60.0:1 93.6 % 6.4 %
100.0:1 96.1 % 3.9 %
200.0:1 98.0 % 2.0 %
400.0:1 99.0 % 1.0 %
800.0:1 99.5 % 0.5 %