"Le Saviez-Vous ?"

daRinze, à mon avis Werber a loupé (as usual) l'intérêt principal du format international.

Si la racine de 2 est utilisée, c'est pour conserver le même rapport entre la longueur et la largeur ce qui permet donc de massicoter différents formats sans avoir de chute de papier.

On parle donc de formats homothétiques.

Autant dire que pour un imprimeur, économie de papier...

Current standard sizes of U.S., Canadian and Mexican paper are a subset of the traditional sizes referred to below. "Letter", "legal", "ledger", and "tabloid" are by far the most commonly used of these for everyday activities. The origins of the exact dimensions of "letter" size paper (8+1⁄2 × 11 in or 215.9 × 279.4 mm) are lost in tradition and not well documented. The American Forest and Paper Association argues that the dimension originates from the days of manual paper making, and that the 11 inch length of the page is about a quarter of "the average maximum stretch of an experienced vatman's arms." However, this does not explain the width or aspect ratio. Outside of North America, Letter size is also known as "American Quarto" and the size is indeed almost exactly a quarter of the old Imperial (British) paper size known as Demy 4to (17½"×22½" ), allowing ½" for trimming.