How to calculate the data rate of LoRa?
Easy way

The easiest way to calculate the data rate is to use the official LoRa calculator that you can download from this link.

Spreading factor is displayed differently compared to the site that the picture is from.



In the program, the spreading factor should be recognized as the exponent of two, as \$2^{12}\$ is 4096 which is the same thing, as in Bw125Cr48Sf4096.

You enter your values on the left, and modifying the values in the green rectangle are changing the equivalent bitrate part on the right, although changing values under Packet Configuration changes the other relevant values for timing,  but doesn't affect the bitrate.



Manual way

If you want to calculate the bitrate manually, the documentation recommends the following method on the bottom of page 3 of the LoRa FAQ.


\$DR = SF \cdot \cfrac{BW}{2^{SF}} \cdot CR\$

DR = Data rate
SF = Spreading factor
BW = Bandwidth
CR = Coding rate


If we substitute the above mentioned example values, we get the following:

\$DR = 12 \cdot \cfrac{125\ kHz}{2^{12}} \cdot \cfrac{4}{8}\$

\$DR = 183.1055\ bps\$.

This is the exact same value what we got in the calculator software.




Sources

LoRa Design Guide
LoRa FAQ