Just apply the same logic based on EIRP (I am using UK Regulatory Values) with 0 = MAX
EIRP
5GHz = 23dBm
5.4GHz = 30dBm
5GHz Example
Gain = 8dBi
Power = 15dBm
5.4GHz Example
Gain = 8dBi
Power = 22dBm
Note: You also you have to check the max TX power capabilities of the AP as when using 5.8GHz in the UK for MESH traffic and certain AP's only support max of 23dBm you are under EIRP in terms of link budget.