Albert Barnes Commentary 2 Kings 18:2

"Twenty and five years old was he when he began to reign; and he reigned twenty and nine years in Jerusalem: and his mother`s name was Abi the daughter of Zechariah." — 2 Kings 18:2 (ASV)

He was twenty-five years old. This statement, combined with that of 2 Kings 16:2, would make it necessary that his father Ahaz married at the age of ten and had a child born to him when he was eleven years old. This is not impossible, but its improbability is so great that most commentators suggest a corruption in some of the numbers.

The Zachariah mentioned here was perhaps one of the “faithful witnesses” of Isaiah 8:2.