dBm to Watt Conversion Chart

dBm = log10 (mW)*10
mW =10^(dBm/10
       
40 dBm   10.00 watts  
36 dBm   4.00 watts < Maximum ERP allowed by FCC in U.S. 
30 dBm   1.00 watts  
27 dBm   500 milliwatts  
26 dBm   400 milliwatts  
25 dBm   320 milliwatts  
24 dBm   250 milliwatts  
23 dBm   200 milliwatts  
22 dBm   160 milliwatts  
21 dBm   130 milliwatts  
20 dBm   100 milliwatts < Maximum ERP allowed by E.T.S.I. In Europe
15 dBm   32 milliwatts  
10 dBm   10 milliwatts  
5 dBm   3.2 milliwatts  
4 dBm   2.5 milliwatts  
3 dBm   2.0 milliwatts  
2 dBm   1.6 milliwatts  
1 dBm   1.3 milliwatts  
0 dBm   1.0 milliwatts  
1- dBm   0.79 milliwatts  
5- dBm   0.32 milliwatts  
10- dBm   0.1 milliwatts  
20- dBm   0.01 milliwatts  
30- dBm   0.001 milliwatts  
40- dBm   0.0001 milliwatts  
50- dBm   0.00001 milliwatts  
60- dBm   0.000001 milliwatts  
70- dBm   0.0000001 milliwatts  
80- dBm   0.00000001 milliwatts < Receive threshold for most WLAN devices