Do your sheets fit on a mattress that are more than 11” thick? January 28, 2022 14:58 Yes. Our sheets are designed to fit mattresses with a thickness of 11 inches to 14 inches. Related articles Do I need a mattress protector? Will the mattress protector make me sleep hot? What is your return policy for sleep accessories? What is the break-in period? Is the mattress protector hypoallergenic? Comments 0 comments Article is closed for comments.