Posted: 2008-11-02 16:09
The length of a dot in milliseconds is 1200/wpm. A dash is three times as long, pauses between letters also three dot-length and a pause between two words is 7 dot-lengths.
This will get you the timing for the PARIS standard (i.e. 60wpm means you can send 60 times PARIS in one minute). It's simple math: A minute has 60 seconds, PARIS (including the space after it) has 50 "elements" (dot-length).
So, for one wpm you'd need a dot length of 60/50 seconds, for x wpm you need a dot length of 60/(x*50) seconds which is the same as 1.2/x (easier to remember)...