From TalkBass Wiki
how to calculate tension:
T = tension in pounds;
UW = unit weight of the string, in pounds per linear inch;
L = vibrating length of the string (for an open string, this would be the scale length-nut to bridge) in inches;
F = frequency of the note to which you will tune the string, in Hz;
1. Everything else being the same, pitch increases as tension increases;
2. Everything else being the same, tension increases as scale length increases(this is nut to bridge);
3. Everything else being the same, tension increases as unit weight increases, thus a heavier gage string will be under greater tension;
http://www.liutaiomottola.com/formulae/tension.htm
(this info is from www.liutaiomottola.com and is copyright © 2004, 2005, 2006, 2007 by R.M. Mottola)
