I am sure conversion from mW to dBm is not an everyday occurrence but never the less I wanted to try this blogspot feature of creating your own mini application. So to remove some rust from my programing skills made a simple program in php to help convert those mW to dBm. Named "mW2dBm" is the first app on the right panel of the blog. Formula for computing dBm is: 10 times Log base 10 of mW that is 10 * log10(mW).
Here's the simple code, case you want to put on a webserver. You will need php and to name the file "mw2dbm.php".
It's an image cause I had no time to check how to put code in a blogspot post.
License is GPL, you can do whatever you want.