I ordered this in 3X with another Cutter & Buck shirt that was 3XB.  So initially I was thinking it was poorly fitting.  I kept working out and it now fits perfectly.  So based on my experience, if you want a 3XB, the 3X in this shirt isn't for you.  And Cutter & Buck quality has always been outstanding.  I just have to keep checking the prices to get the best deal.