How to Calculate measured power - iOS

I had set the Transmit Power (Tx) as -8dBm and Advertising Interval to 960 ms. Can you please tell me how to calculate the range/measured power in meters ? I’m on iOS

What exactly do you want to calculate and what for? Range and measured power are two different concepts (:

Let me explain my use case. I have each beacon in two rooms, each room is about 20-25 meters away. When i’m near (say about 5 meters away) from Room1, i need to range the beacons in the room1, stop ranging the beacons in room 2 and hit web service. When i’m near (say about 5 meters away) from Room 2, i need to range the beacons in room 2, stop ranging the beacons in room 1 and hit web service.

I’m checking the region identifier -(void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region in this method. When identifier is ‘room1’, i’m start ranging the beacons in room1 and stop ranging the beacons in room2. When identifier is ‘room2’, i’m start ranging the beacons in room2 and stop ranging the beacons in room1. When i walk towards room1, it is identifying the region and when walk towards room2, it is identifying the region. But the problem is when i walk towards room1 from room2, it is not identifying the room1 region.

My desired output : When i’m near (say 5 meters away) from room 1, it should start ranging the beacons and when beacon proximity (or any other determining factor, like, rssi) is immediate/near (or using some other calculation), i need to hit web service. Like wise, it should work the same way for room 2 as well. Can you please let me know the better approach. The proximity factor is fluctuating a lot, even when i’m near the beacon, it sometime says far, so i want the different determining factor.