at the lowest point between the front and back legs- maybe 8-9 inches to the bottom of the belly. The top of the back may be 24-30 inches high depending on the size of the pig except on a real bruiser.
I think hogs with a lot of Russian or European strain in them would average bigger than the hogs I see on the east coast..which are descendants of Spanish pigs dropped off on our coastline in the 1600's and domestic breeder pigs that have gotten loose or been turned loose and mixed with the Spanish hogs.