The amount of PSA is generally related to prostate size and the prostate typically enlarges as men age. Overall, a PSA level of up to 4.0 ng/ml is considered normal for men older than 60, and 2.5 ng/ml is the upper normal range for men age 60 or younger. These are rough guidelines because some younger men will have enlarged prostates and some older men will have normal-sized glands. Furthermore, prostate cancer can occur with PSA less than 2.5 ng/ml.