Paper Sizes A0 to A10: Dimensions in mm, cm, inches and pixels
How big is an A4 sheet exactly? What about A3 or A6? The A series, defined by the international ISO 216 standard, governs nearly every paper size in the world except in North America. Here is the complete table of dimensions from A0 to A10 in millimeters, centimeters, inches and pixels, with guidance on choosing the right size.
| Size | mm | cm | Inches | Pixels (300 DPI) | Pixels (72 DPI) |
|---|---|---|---|---|---|
| A0 | 841 × 1189 | 84,1 × 118,9 | 33,11 × 46,81 | 9933 × 14043 | 2384 × 3370 |
| A1 | 594 × 841 | 59,4 × 84,1 | 23,39 × 33,11 | 7016 × 9933 | 1684 × 2384 |
| A2 | 420 × 594 | 42,0 × 59,4 | 16,54 × 23,39 | 4961 × 7016 | 1191 × 1684 |
| A3 | 297 × 420 | 29,7 × 42,0 | 11,69 × 16,54 | 3508 × 4961 | 842 × 1191 |
| A4 | 210 × 297 | 21,0 × 29,7 | 8,27 × 11,69 | 2480 × 3508 | 595 × 842 |
| A5 | 148 × 210 | 14,8 × 21,0 | 5,83 × 8,27 | 1748 × 2480 | 420 × 595 |
| A6 | 105 × 148 | 10,5 × 14,8 | 4,13 × 5,83 | 1240 × 1748 | 298 × 420 |
| A7 | 74 × 105 | 7,4 × 10,5 | 2,91 × 4,13 | 874 × 1240 | 210 × 298 |
| A8 | 52 × 74 | 5,2 × 7,4 | 2,05 × 2,91 | 614 × 874 | 147 × 210 |
| A9 | 37 × 52 | 3,7 × 5,2 | 1,46 × 2,05 | 437 × 614 | 105 × 147 |
| A10 | 26 × 37 | 2,6 × 3,7 | 1,02 × 1,46 | 307 × 437 | 74 × 105 |
How does the A series (ISO 216) work?
The A series is built on an elegant idea: every size has a height-to-width ratio equal to the square root of 2 (about 1.414). This proportion has a unique property: folding a sheet in half across its width yields exactly the next smaller size, with no waste or margin. So two A4 sheets side by side make an A3, and an A4 folded in half gives two A5.
The base size is A0, which has an area of exactly one square meter. Each following size (A1, A2, A3…) has half the area of the previous one. This logic makes enlarging and shrinking effortless when printing: going from A4 to A3 doubles the size without distorting the content, which explains the standard's worldwide success.
Which paper size should you choose?
A4 (210 × 297 mm) is the standard for everyday documents: letters, reports, invoices, contracts and office printing. A3 (297 × 420 mm), twice as large, is used for posters, plans, tables and presentations. A5 (148 × 210 mm) suits flyers, notebooks and booklets, while A6 (105 × 148 mm) is the classic postcard size.
The large A0 and A1 sizes are reserved for posters and architectural plans, while the very small sizes (A7 to A10) are used for labels, tickets and business cards. If your PDF is not the right size, the crop tool adjusts margins, nup groups several pages per sheet, and image-to-pdf builds a PDF at the size you want from images.
Dimensions in pixels: the role of DPI
A paper size is expressed in millimeters, but for an image or a PDF meant for screen or print you need to convert it to pixels. The pixel count depends on the resolution in DPI (dots per inch): pixels = inches × DPI. For example, an A4 is 8.27 × 11.69 inches; at 300 DPI (print quality) that gives 2480 × 3508 pixels, and at 72 DPI (screen), 595 × 842 pixels — exactly the size of an A4 page in PDF points.
For professional printing, aim for 300 DPI; for web display, 72 to 96 DPI is enough. The table above provides both values for each size. A higher resolution makes the file heavier: if your PDF becomes too large, the compress tool reduces its weight, and convert exports your pages as images at the resolution you choose.
Frequently asked questions
What are the dimensions of an A4 sheet?
An A4 sheet is 210 × 297 millimeters, i.e. 21 × 29.7 cm or 8.27 × 11.69 inches. At 300 DPI that is 2480 × 3508 pixels.
How many A4 fit in an A0?
An A0 contains 16 A4 sheets. Each A-series size has half the area of the previous one: an A0 equals 2 A1, 4 A2, 8 A3 or 16 A4.
Is A4 the same everywhere in the world?
A4 is the standard in almost every country through the ISO 216 norm. The United States and Canada use the Letter size (216 × 279 mm), which is slightly different.
How many pixels is an A4 at 300 DPI?
An A4 at 300 DPI is 2480 × 3508 pixels. At 150 DPI it is 1240 × 1754 pixels, and at 72 DPI, 595 × 842 pixels.