How long can a US President stay in office?

Terms for US Presidents

Under the rule of the 22nd Amendment, US presidents can serve two four-year terms of office, and a maximum of 10 years if succeeding a President for less than half of a full term.

Amendment XXII:

Section 1. No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once. But this article shall not apply to any person holding the office of President when this article was proposed by the Congress, and shall not prevent any person who may be holding the office of President, or acting as President, during the term within which this article becomes operative from holding the office of President or acting as President during the remainder of such term.