Costco covers mattresses under its risk-free 100% satisfaction guarantee. Costco's own policy page carves out specific categories with fixed windows — electronics at 90 days, for example — and mattresses are not among them, so there is no published deadline.
WHAT THAT MEANS IN PRACTICE. Members regularly return mattresses long after the point at which a direct-to-consumer brand's trial would have expired. It is a genuine advantage, but it is a satisfaction guarantee, not a contractual trial length, and Costco can decline abuse.
NO RESTOCKING FEE. Costco's policy text states no restocking fee for this kind of merchandise.
IN WAREHOUSE VERSUS ONLINE. Warehouse purchases go back to the warehouse, with the original packaging where possible. Costco.com orders can be started in your account, but Costco publishes a self-service return exclusions list — large items such as mattresses may need a call rather than a click.
WHAT COSTCO DOES NOT PUBLISH. Costco does not state what happens to a returned mattress, whether it collects large items from your home, or a refund-timing window. Ask when you open the return.
THE TRADE-OFF. Costco's mattress selection is narrower than a brand's own site and the models are often retailer-specific versions, which makes cross-shopping harder. The return policy is the strongest reason to buy there.