A Flat Bed Sheet is a large piece of cloth normally used as a top sheet or used to cover a mattress.

A flat bed sheet or top sheet is generally laid on top of the fitted bed sheet or bottom sheet covering the mattress. One sleeps between the two bed sheets. Blankets, duvets, bedspreads and other bed covers are then placed on top of the flat bed sheet.

A flat bed sheet is simply a rectangular sheet of cloth, while a fitted bed sheet has its four corners, and sometimes two or four sides, fitted with elastic, to be used only as a bottom sheet. The use of hospital corners a particular way of folding and tucking while making the bed is sometimes used when the bottom sheet is a flat bed sheet rather than fitted bed sheet.

Flat bed sheets were traditionally white, but now various colours and patterns are used. The quality of a flat bed sheet is regularly conveyed by the number of thread or number of threads per square inch of material. In general, the higher the thread count, the softer the sheet, but the weave and type of thread may affect the type of the material so that a sheet with a lower thread count may actually be softer than one with a higher count.

There are lots of different quality flat bed sheets available, Poly / cotton flat bed sheets, Poly / cotton Percale flat bed sheets, 400 thread count Egyptian Cotton flat bed sheets, 100% Cotton Flannelette flat bed sheets and 800 thread count Egyptian Cotton flat bed sheets.