Some argue that the Bible is contradictory concerning how old Jehoiachin was when he became king. The argument is that 2 Kings 24:8 says that Jehoiachin was eighteen years old when he became king, but 2 Chronicles 36:9 says that he was eight years old when he became king. However, there are at least two reasonable explanations that solve this alleged contradiction in the Bible.
Jehoiachin was eighteen years old when he became king, and he reigned three months in Jerusalem. His mother’s name was Nehushta the daughter of Elnathan of Jerusalem.2 Kings 24:8
Jehoiachin was eight years old when he began to reign, and he reigned three months and ten days in Jerusalem: and he did that which was evil in the sight of the Lord.2 Chronicles 36:9 (KJV)
Jehoiachin was eighteen years old when he became king, and he reigned three months and ten days in Jerusalem. He did what was evil in the sight of the Lord.2 Chronicles 36:9 (ESV)
There are at least two reasonable explanations that would resolve this alleged contradiction in the Bible:
It is possible that Jehoiachin was appointed co-regent with his father when he was eight years hold, and he actually became king when he was eighteen years old.
There is precedence in Scripture of Israelite kings appointing kings even while they are still alive. For example, 1 Kings 1:33-40 says that David appointed Solomon as king even while David was still alive, and 2 Chronicles 26:21 says that Jotham was appointed co-regent with his father Uzziah when Uzziah had leprosy.
33 And the king said to them, “Take with you the servants of your lord and have Solomon my son ride on my own mule, and bring him down to Gihon. 34 And let Zadok the priest and Nathan the prophet there anoint him king over Israel. Then blow the trumpet and say, ‘Long live King Solomon!’ 35 You shall then come up after him, and he shall come and sit on my throne, for he shall be king in my place. And I have appointed him to be ruler over Israel and over Judah.” 36 And Benaiah the son of Jehoiada answered the king, “Amen! May the Lord, the God of my lord the king, say so. 37 As the Lord has been with my lord the king, even so may he be with Solomon, and make his throne greater than the throne of my lord King David.”
38 So Zadok the priest, Nathan the prophet, and Benaiah the son of Jehoiada, and the Cherethites and the Pelethites went down and had Solomon ride on King David’s mule and brought him to Gihon. 39 There Zadok the priest took the horn of oil from the tent and anointed Solomon. Then they blew the trumpet, and all the people said, “Long live King Solomon!” 40 And all the people went up after him, playing on pipes, and rejoicing with great joy, so that the earth was split by their noise.1 Kings 1:33-40
And King Uzziah was a leper to the day of his death, and being a leper lived in a separate house, for he was excluded from the house of the Lord. And Jotham his son was over the king’s household, governing the people of the land.2 Chronicles 26:21
The ESV translates 2 Chronicles 36:9 with “eighteen,” has has this footnote:
Septuagint (compare 2 Kings 24:8); most Hebrew manuscripts ”eight”Footnote for 2 Chronicles 36:9, ESV
It is reasonable to believe that the number “eight” is because of a copyist error, since the difference between the Hebrew characters for “eight” and “eighteen” is very small.
There are some foundational principles that apply to all alleged and apparent contradictions in the Bible. To read more, see Bible Difficulties: Foundational Principles.
To read more answers to alleged and apparent contradictions in the Bible, see “Contradictions” in the Bible Answered.
These books are also excellent resources: