The normal range of PSA levels in the blood can vary depending on a person's age. It is less than 2.5 ng/mL (for those under 40 and between 40-49), less than 3.5 ng/mL (ages 50-59), less than 4.5 ng/mL (ages 60-69), and less than 6.5 ng/mL (ages 70 or older.