Q: WHAT YEAR DID AHAZ'S REIGN END IN JUDAH?
A: IT DEPENDS WHAT CALENDAR YOU ARE USING!
On the Gregorian calendar (the one you might have on your wall) the year was 661 BC.
On the Hebrew calendar, sometimes called the biblical calendar, the year was 3386 AM.
2 Kings 16:2 – Twenty years old was Ahaz when he began to reign, and reigned sixteen years in Jerusalem, and did not that which was right in the sight of the Lord his God, like David his father.