Silicon Labs provides an RF range calculator for customers to help estimating the actual range for their wireless applications:
The range depends on the following parameters:
The range calculator provides 3 options for TX:
The possible options for RX are the following:
A typical range calculation is shown below.
The calculation uses an output power of 13dBm and a receiver sensitivity of -100dBm. Assuming 0dBi antenna gain for both TX and RX, the typical line of sight range at 868MHz is ~1000m.
Note: The calculation provides a good approximation on the expected range, however the range strongly depends on the propagation factor (environment). Using a propagation factor value of 4 (typical for indoor environment) results ~150m range if all other parameters remain the same as in the above example.