Do your sheets work on a mattress over 11" thick? April 13, 2022 19:32 Updated Yes, our sheets are designed to fit mattresses with a thickness from 11" to 14". Related articles Can I adjust the firmness of the premium shredded foam pillow? What is the size and weight of the mattress box? Can I delay a shipment? Are shipping fees refundable? What if my mattress feels too firm?