US does not use A paper sizes. Ha! I do know my paper sizes
The U.S., Canada and Mexico use a different system of paper sizes compared to the rest of the world. The current standard sizes are unique to that continent, although due to the size of the North American market and proliferation of both software and printing hardware from the region, other parts of the world have become increasingly familiar with these sizes (though not necessarily the paper itself). The traditional North American inch-based sizes differ from those
described 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 (81⁄2 in × 11 in or 215.9 mm × 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."
[9] However, this does not explain the width or aspect ratio. Outside of North America, Letter size may also be known as "American Quarto"
[10] and the size is indeed almost exactly one quarter of the old Imperial (British) paper size known as Demy 4to (17½"×22½"), allowing ½" for trimming.
[11]
North American paper sizes
Sizein × inmm × mmSimilar Canadian P size
Letter8.5 × 11215.9 × 279.4P4: 215 × 280
Government-Letter8.0 × 10.5203.2 × 266.7
Legal8.5 × 14215.9 × 355.6
Junior Legal8.0 × 5.0203.2 × 127
Ledger[12]17 × 11432 × 279
Tabloid11 × 17279 × 432
A8 paper, on the other hand - the size of a couple of stamps, whereas the A8 is a big car.
