The next presidential term starts January 2021.
Joe Biden age chart:
Birthday-November 20, 1942 (age 76 years)
year 19 20 21 22 23 24 25 26
age 77 78 79 80 81 82 83 84
Bernie Sanders age chart:
Birthday-September 8, 1941 (age 77 years)
year 19 20 21 22 23 24 25 26
age 78 79 80 81 82 83 84 85