PSA Doubling Time Calculator Enter First PSA: Enter Second PSA: Enter Interval between PSA values in months: Click this button to calculate PSA Doubling Time PSA Doubling Time is: Months References for PSA Doubling Time: (1) Cannon GM et al. Urology. 2003; 62 (Suppl 6B): 2-8 (2) Roberts SG et al. Mayo Clin Proc. 2001; 76: 576-581