Estimated coverage points are calculated based on the signal strength of all radios providing coverage to a hex. Radios with the strongest signal level in the hex split the modeled coverage points equally for providing coverage in a given hex. Currently, the calculation implemented in the Coverage Map does not follow all the nuances outlined in HIP74, like the five radio limit.
A single radio can cover multiple hexes and earn points for each, depending on the signal strength and presence of coverage by other radios. Indoor and outdoor radios earn different amounts of estimated coverage points for the same signal strength. You can find more explanation here.