Once you've got the chest number, there are a few extras that make or break an oversized fit:

• Shoulder seam: On a regular tee, the seam sits right on your shoulder bone. On an oversized one, it should fall an inch or two past that. If the size chart lists shoulder width, add 1–2 inches to your own shoulder measurement.
• Body length: Oversized doesn't mean long. It means wider, with a length that hits mid-hip or slightly below. If you're shorter (under 5'9"), a longer body can overwhelm you—look for a cropped oversized option or size down.
• Fabric weight: This is where GSM matters. A heavier tee (180 GSM or more) holds its shape, so the oversized cut looks intentional. A lighter tee (like 150 GSM) can cling and wrinkle, making you look like you grabbed the wrong size. If you're between weights, go heavier for a cleaner silhouette.