FAQ MATTRESSES WILL MY SHEETS FIT ON A CASPER? SEE ALL QUESTIONS WILL MY SHEETS FIT ON A CASPER? As long as your sheets are compatible with a 12 inch high mattress, they will absolutely fit on any of the Casper mattresses! We recommend using Casper sheets for the best sleep environment possible. YOU MAY ALSO LIKE Can I use a box spring? What is Supima® or Pima® Cotton? Will Casper sheets only fit on a Casper mattress? How should I wash my sheets?