User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-4649443-20121216203303

I measured Percy's height according to Riptide in the covers and discovered:

Lightning Thief: about one and a half swords=about five-foot-six

Battle of the Labyrinth: almost two swords=about five-foot-ten

Between BotL and TLO=grew one inch

Between TLO and SoN=grew one inch

Percy is about 6 feet.