Hi Stan,
From show run-config, you will find the following:
Tx Power Level 1 .......................... 20 dBm
Tx Power Level 2 .......................... 17 dBm
Tx Power Level 3 .......................... 14 dBm
Tx Power Level 4 .......................... 11 dBm
Tx Power Level 5 .......................... 8 dBm
Tx Power Level 6 .......................... 5 dBm
Tx Power Level 7 .......................... 2 dBm
Tx Power Level 8 .......................... -1 dBm
Note that every power level is a 3dBm step. So, Tx Power Level 3 would be 25mW.
-Matt