Paper Sizes
Exact dimensions for every standard paper size — switch between mm, cm and inches.
| Size | Series | Width | Height |
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Every standard paper size in one place
This chart lists the international ISO 216 paper sizes (the A and B series used almost everywhere outside North America) and ISO 269 C-series envelope sizes, alongside common North American sizes such as Letter, Legal and Tabloid. Each size shows its exact width and height, and you can switch between millimeters, centimeters and inches with one tap. Search by name to jump straight to A4, A3, Letter or any other format.
How ISO paper sizes work
The ISO A series is built on a simple rule: every size has an aspect ratio of 1:√2, and cutting a sheet in half across its longer side produces the next size down. A0 has an area of exactly one square meter, A1 is half of A0, A2 is half of A1, and so on. That is why scaling a document from A4 to A3 keeps the layout perfectly proportional. The B and C series follow the same ratio with different starting areas, which is why a C4 envelope neatly holds an unfolded A4 sheet.
FAQ
What is the size of A4 paper? A4 is 210 × 297 mm, which is 21 × 29.7 cm or about 8.27 × 11.69 inches.
Is Letter the same as A4? No. US Letter (215.9 × 279.4 mm / 8.5 × 11 in) is wider and shorter than A4, so documents do not map exactly between the two formats.
Why is A3 exactly double A4? Because the ISO system halves the long edge at each step, A3 has twice the area of A4 while keeping the same 1:√2 proportions.
Which paper fits in a C4 or C5 envelope? A C4 envelope fits an unfolded A4 sheet, a C5 fits an A4 folded once (to A5), and a C6 fits an A4 folded twice.