Find the distance to Eddystone beacon from the device using Android Beacon Library

I am developing an android application to find the distance from Eddystone beacon to the mobile device. I am using Android Beacon Library and following this example. when I locate my beacon nearly 1 meter away from my device, it shows like below. it shows small values and changes continuously. How to solve this and get at least nearly accurate value.

The "underestimate" shown in the question suggests one or more of the following may be true:

1. The Beacon has not been calibrated.
2. The receiving phone device model may have an unusually high measurement of signal strength requiring a device-specific adjustment of its distance calculation.

See here for more information on how to address these issues.

Even once you address the above, set your expectations properly. Bluetooth LE distance estimates are rough. They are useful for telling you if another device is within a couple of meters or many meters away. But they cannot tell you the precise distance to a bluetooth transmitter.