13″x 18″ IS THE ACTUAL USABLE SIZE Thickness: 550 GSM Paper Board/28PT (Heavy Duty) White exterior with Brown interior for privacy! Great for shipping items like Legal Documents, Art Boards, 11″ x 14″ Photos, etc. Premium Quality: These mailers are made extremely durable, strong seams & adhesive like permanent glue yet very light in weight! Simply pack, peel and seal! Lower shipping cost for your business! Approved by USPS, FedEx, UPS, DHL, etc. 100% recyclable! ***Need large quantity or have questions? Please message us! Thanks