Theres more than one way to calculate BPM, the traditional way is to take a stopwatch
, count the number of beats and stop when the stopwatch hits 60. This can lead to skewed numbers, like 140.7 BPM. There are two more ways to my knowledge, the quickest being the 17 beat system. You take said stopwatch, start the stopwatch
on a beat, and stop it after you have counted 17 beats
17*(60/X) = BPM (X being the number in seconds that you counted)
ie. 17 seconds, for 17 beats would give you an equal 60BPM.
The other way is called the 16 Bar system, this is similar to the 17 beat system, but you have to count 16 bars, traditionally there are 4 beats in a bar. So, you must count 64 beats.
64*(60/X) = BPM
This yields a better result, as the more beats you count the more accurate it is.