If you want to convert the wait value to beats per minute, take 60000 and divide it by the product of the wait value and the number of clicks per beat (which is normally 4).
To convert beats per minute to wait, take 60000 and divide it by the product of beats per minute and the number of clicks per beat.
So say you want a song to play at 150 beats per minute, and there are 8 clicks per beat. 60000/(150*8) = 60000/1200 = 50, so your wait value would be 50.
The formula works because of dimensional analysis
milliseconds/click * clicks/beat * beats/minute = milliseconds/minute
The three quantities on the left are variable, but the number of milliseconds in a minute is always 60000.
edit: also this
To convert beats per minute to wait, take 60000 and divide it by the product of beats per minute and the number of clicks per beat.
So say you want a song to play at 150 beats per minute, and there are 8 clicks per beat. 60000/(150*8) = 60000/1200 = 50, so your wait value would be 50.
The formula works because of dimensional analysis
milliseconds/click * clicks/beat * beats/minute = milliseconds/minute
The three quantities on the left are variable, but the number of milliseconds in a minute is always 60000.
edit: also this