What size is my bed, and what fits it

Mattress names are not measurements, and a fitted sheet that almost fits is a sheet that comes off at four in the morning.

Measure the depth, not just the top

Twin, Full, Queen and King describe the top of the mattress. They say nothing about how deep it is, and depth is what decides whether a fitted sheet stays on. A modern mattress with a topper can be sixteen inches. A older one can be eight. Measure from the top surface down to where the base begins, and buy for that number.

Why a flat sheet is sized differently

A flat sheet has to cover the mattress and tuck in on three sides, so it is cut much wider than the mattress itself. That is why a Queen flat sheet looks oversized when it arrives. If you do not tuck, size down and you will have less cloth to wrestle.

Duvet covers and the gap at the foot

A duvet cover should match the insert, not the mattress. Putting a Queen insert in a King cover leaves the cover to slide, which is the noise people blame on the ties. Match the two, use the corner ties, and the problem disappears.

When to size up

Size up if two people pull the covers in opposite directions, if the mattress is deeper than fourteen inches, or if you want the cover to hang over the sides rather than sit on top. Everywhere else, buy the size on the label.