What is the maximum range achievable by my radio pair?

A very common question is "what is the maximum range of my radio pair?", for example "What range can I get out of a pair of NanoBridge M5-22 radios?". The Free Space Path Loss formula can help us answer this question; by re-arranging the formula and entering Frequency and Link Budget (to derive tolerated path loss for a target RSSI) we can determine the maximum range of a radio pair. This, of course, assumes that we have perfect line-of-sight, and no Fresnel Zone incursions.