For how long was David king of only Judah?

David was king of only Judah for a period of approximately 7.5 years. This timeframe is derived from biblical accounts, primarily found in 2 Samuel. After the death of Saul, David initially became king over the tribe of Judah while Ishbosheth, Saul's son, was made king over the northern tribes of Israel. David's reign in Hebron, where he was king of Judah, lasted until he united the entire kingdom of Israel under his rule, which eventually occurred after the death of Ishbosheth. This period is significant as it illustrates the challenges and complexities of his rise to power and the political landscape of the time. Therefore, the choice stating that David ruled only Judah for 7.5 years accurately reflects the biblical record.