Measurements:

Pit to Pit: 17 seam to seam, but that's with dropped pit seams, fits more like 18.5~19 across
Sleeve Length: 13.5
Total Length: 25

Shoulders: 18.5~19

Looks awesome! VERY rare football style t-shirt from the 70's by Champion with a Champion Products label at the bottom waist plus old tag in the collar. True vintage single stitch with heavier cotton, USA made with extra crossbar seam and 3/4 sleeves for the Football jersey styled tee. The sleeves/pits have a lower starting point than most standard t-shirts also found in these football tees, so keep in mind with the measurements the seam to seam across the pits isn't actually how it fits, the actual pit to pit sits above where the seams lie by just a bit, then fits more snugly below along the waist. If you aren't familiar with this, notice the shoulder measurement is actually bigger than the pits and that's more of an indicator as to the normal fit if you compare it to more standard tees.