I just finished reading an illuminating article by Daniel Hays about Goliath’s height. I was not aware that there is a textual variant at this point in the text (as well as many other points in 1-2 Samuel, and the story of David and Goliath in particular), but there is. While the Masoretic Text contains the 9’9” version we are all familiar with (most English translations of the OT use the Masoretic text), there are earlier manuscripts and translations that say he was 6’9”. Hays shows how both the external and internal evidence support the 6’9” reading over the 9’9” reading. Check it out.