Paper Sizes in different countries
United States and CanadaIn the United States and Canada the normal size of paper is called letter size, or sometimes US letter. It is 8½ inches wide and 11 inches long.
The other common size of paper in the US is called legal, or sometimes US legal. It is also 8½ inches wide, but it is 14 inches long. It is similar to the size called foolscap in Britain.
Europe and other placesIn Europe and other places an international system of paper sizes is used. The normal size of paper is called A4. It is measured in metric. It is 210 millimeters wide and 297 millimeters long. This is about the size of US letter, but it is a little narrower, and a little longer.
In the international paper size system, the sizes are based on mathematical formulas. A0 is the biggest at 1 square metre. A1 is half as big as A0. A2 is half as big as A1, and so on. The sizes with "B" and "C" in their name are in between the "A" sizes.