Here is a quick APPROXIMATE mapping between the number of bars on the cell phones and the signal strength in dBm. By the way, the reason signal strength shows with a negative sign is that it is measured as base-10 log of the signal strength. Therefore, 1/10 will be -1, 1/100 will be -2, 1/1000 will be -3 and so on. Therefore, the signal strength as measured in dBm increases or decreases progressively by a factor of 10. Of course, you will notice that we are dealing with very tiny numbers here. How big is 10-110!
Signal Strength in dBm | Approximate Number of Signal Strength Bars on Cell Phones |
-114 to -108 | 1 bar |
-107 to -98 | 2 bars |
-97 to -94 | 3 bars |
-93 to -90 | 4 bars |
-89 and above | 5 bars |
