In the Ancient Near East, there was no universally-accepted calendar. The same kinds of “discrepancies” are found in every kingdom’s annals.
In this April 30 Chalcedon blog post, Mark Rushdoony tackles the question of whether the Bible is accurate as to matters of historical fact.
Critics like to point to supposed “discrepancies” within the Bible: for example, when it comes to stating how many years were in the reign of a king of Israel or Judah. At that point in world history, there was no widely-accepted standard of timekeeping, no universal calendar. Nor, within the same kingdom, was there any agreement as to when a king’s reign actually began or ended. So naturally the numbers will differ, here and there.
The point is, the Bible is 100% reliable and, as the Word of God, 100% authoritative–even when we can’t understand some of the historical details.
If your faith stands or falls by how well the numbers tally in Kings and Chronicles, there’s not much to it.