How to calculate the required internet speed?

Question

Computer networks

Good afternoon.
Actually the question is: how to calculate the required Internet speed for an enterprise?
Of course, you can use the 2mb/sec per user formula recommended by everyone, but it seems to me _extremely_ conditional and not practical. Yes, and she does not explain what to do if the enterprise has a VPN with another office for using a common file storage, a pack of VoIP phones and, say, several always active RDP sessions.
Thank you for your attention.

Answer 1

Or model theoretically - the more accurate the input data, the better.
Or measure the need on a small sample and extrapolate to the number of employees.
The task, if we ignore the subject area, is typical and has been solved thousands of times. Both of the described paths have pitfalls (the first requires immersion in probability theory, because you need to evaluate the load on the specified VoIP phones, peak and average loads on RDP, etc.; the second requires correct sampling of a small sample with so that all "kinds" of collaborators and again the theory of probability get into it).
+ It is always recommended to evaluate two values ​​- average and peak load, and then take some overestimation from the average, depending on what the peak turned out to be.