Full terms . . . two, as answered by others, above.
Presidential trivia: What is the maximum amount of time a person can serve in the office of President of the United States of America? . . .
Answer: One day less than ten years. A person can only be elected to two 4 yr. terms = 8 years; however, if a Vice President becomes President because of the President's incapacity or death, if he serves 2 years or more, it counts as as a term against him and he could then only be elected to one more term. If the V.P. serves "less that 2 years" of another's term, then it doesn't count against the 2 term limit . . . therefore, a person can serve up to 9 years 364 days as President, maximum . . .