Do Your Sheets Work on a Mattress Over 11" Thick? March 30, 2022 20:08 Updated Yes, our sheets are designed to fit mattresses with a thickness from 11" to 14". Related articles Is there anything I can do to help prolong the life of my mattress? How do I Choose the Correct Loft for My Pillow? Are Your Pillows Washable? What If My Mattress Feels Too Firm? Can I Adjust the Firmness of the Premium Shredded Foam Pillow?