How paper size converter works
The tool holds exact dimensions for seventeen paper sizes: the ISO A-series from A0 to A10 (defined in millimetres by the √2 aspect-ratio folding rule) and the common US sizes — Letter (8.5 × 11 in), Legal (8.5 × 14 in), Tabloid and Ledger (11 × 17 in), Executive and Statement. Pick a size and an orientation, and it reports width and height in millimetres and inches plus the sheet area in cm² and in².
US sizes are stored as exact fractions of an inch and converted at 25.4 millimetres per inch, so Letter is exactly 215.9 × 279.4 mm. ISO sizes are exact millimetre values rounded to the nearest millimetre by the standard itself — A4 is 210 × 297 mm, which converts to 8.27 × 11.69 inches. Landscape orientation simply swaps width and height; nothing else changes.
Because the two families answer "will this print without scaling?" constantly, the result also checks whether the chosen size fits inside portrait Letter and portrait A4. A5 and Statement slip inside both; A4 fits inside neither Letter (too tall) nor A4's own boundary is the reference — while Letter is too wide for A4. That single pair of flags resolves the classic international print mix-up before it happens.