You'll want to go one size up if you're looking for a looser fit or plan on layering under the jersey. Specifics from Nike Authentic NFL shield at
Patrick Mahomes Kansas City Chiefs Nike Super Bowl LIV Game Jersey Men's NWT NFL
Kansas City Chiefs #15 Patrick Mahomes Super Bowl LIV White Vapor Untouchable Limited Stitched Jersey
Super Bowl LVII: Eagles will be wearing green jerseys vs. Chiefs – NBC Sports Philadelphia