Demy

The traditional British book paper, 22½ by 17½ inches, and still a trim size in publishing.

Demy was the book trade’s sheet. Most nineteenth-century British books were printed on it, folded into octavo or quarto, and the name survives in publishing to describe the resulting page rather than the sheet it came from — a demy octavo is still a recognised British book size.

Like crown, demy doubles exactly: 393.75 square inches becomes 787.5 for double demy and 1,575 for quad demy. A printer could step up a job without the arithmetic going soft, which mattered when the alternative was waste.

The name comes from the French demi, meaning half, which has caused two centuries of confusion because a demy sheet is not half of anything in the British series. The likeliest explanation is that it arrived with the size from Continental mills and kept a name that made sense in its original system, though we have not found that stated in a source we would rely on.