twin-size

or twin-sized

[twin-sahyz]

adjective

(of a bed) approximately 39 inches (99 cm) wide and between 75 and 76 inches (191 and 193 cm) long; single.
pertaining to or made for a twin-size bed: twin-size sheets.

Compare full-size, king-size, queen-size.

Origin of twin-size

First recorded in 1925–30

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for twin-size

Contemporary Examples of twin-size

The mother carries what looks like a twin-size cotton futon mattress.
Whatever You Do Someone Will Die. A Short Story About Impossible Choices in Iraq
Nathan Bradley Bethea
August 31, 2014