What is the full inflation size of the p.ball? Naomi O. January 17, 2020 08:00 Updated Follow The full inflation size of the P.ball is 19.5" - 20.5" in circumference. Related articles What is the p.ball? What is the p.band? I have a small fit ball - can I use that in place of the P.ball? Do the gliders work on carpeted floors? How can I stream/cast the workouts to my TV? Comments 0 comments Article is closed for comments.