Michael Hulse compiled a super-helpful Printful Guideline Cheat Sheet for what size artwork goes on what size Printful t-shirt (Men, Women & Youth T-Shirts).

Artwork sizes for Printful t-shirts

Artwork size: 12” x 16”

Pixels: 3600px x 4800px
DPI: 300

Men / Unisex: Small and larger
Women: X-Large and larger
Youth: Medium, Large, X-Large

Artwork size: 10” x 12”

Pixels: 3000px x 3600px
DPI: 300

Men / Unisex: X-Small
Women: Small, Medium, Large
All Youth sizes, except American Apparel 2yrs
American Apparel 2201
Youth: 8yrs, 10yrs, 12yrs
Anvil 990B
Youth: X-Small, Small

Artwork size: 7” x 8”

Pixels: 2100px x 2400px
DPI: 300

Kids: 2yrs, 4yrs, 6yrs
American Apparel 2105