transformation of dBm/MHz into dBm/GHz

Hi All,
in FCC regulations the Poawer spectral density is defined in dBm/MHz. how could i transform this in UWB/GHz?

is this true:

0dbm/MHz = 1mW/MHz=(1mw*10^3)/GHz =(0+30)dBm/GHz=30dBm/GHz?

Thank you

Where do you see UWB spectral power definitions in FCC with GHz bandwidth? There are specifications with 1 kHz, 1 MHz and 50 MHz resolution bandwidth. Also respective ETSI specifications are using similar limit values.

Calculating dBm/Ghz spectral density is possible but doesn't seem to make much sense.