his arms are at least 21inches in the off season,and over 20 in contest shape.If not bigger.I know pros exaggerate about measurements,but those of you who are saying 18,or 19 are not very well educated in the area.hes about 5ft8,and his arms are thick bis and Tris.Ronnie told me his are 23.I'm not a pro but mine are almost 22.Larry Scott at 5ft6,in the 1960s had 20 in arms.You can go to any gym and find someone with 19 inch arms.So a pro,who's known for thick dense arms are at least 21 off season,maybe bigger.