ISO A-Series Paper Sizes (A0 to A10) in mm, Inches and Points
The A-series is the paper system used almost everywhere outside North America. Every size is exactly half of the one before it, which is why a sheet of A3 folds into two A4 pages with nothing wasted. Here are all the sizes in the units you will meet in a PDF.
A0 to A10 size table
| Size | mm | inches | PDF points |
|---|---|---|---|
| A0 | 841 x 1189 | 33.11 x 46.81 | 2384 x 3370 |
| A1 | 594 x 841 | 23.39 x 33.11 | 1684 x 2384 |
| A2 | 420 x 594 | 16.54 x 23.39 | 1191 x 1684 |
| A3 | 297 x 420 | 11.69 x 16.54 | 842 x 1191 |
| A4 | 210 x 297 | 8.27 x 11.69 | 595 x 842 |
| A5 | 148 x 210 | 5.83 x 8.27 | 420 x 595 |
| A6 | 105 x 148 | 4.13 x 5.83 | 298 x 420 |
| A7 | 74 x 105 | 2.91 x 4.13 | 210 x 298 |
| A8 | 52 x 74 | 2.05 x 2.91 | 147 x 210 |
| A9 | 37 x 52 | 1.46 x 2.05 | 105 x 147 |
| A10 | 26 x 37 | 1.02 x 1.46 | 74 x 105 |
Sizes are width x height in portrait. PDF points are rounded to whole numbers here; the exact A4 is 595.28 x 841.89 pt.
Why every size is half of the last
A0 is defined as one square metre of area with sides in the ratio 1 : 1.4142 (the square root of 2). Cut a sheet across its long side and each half keeps the same ratio, so scaling a design from A4 to A3 changes its size but never its shape.
Check a PDF against the series
Open the file in PdfRuler; the page width and height are shown at the bottom right in your unit. A file that reads 210.00 x 297.00 mm is A4. If it reads 209.97 x 296.97 mm it was most likely made from points that were rounded, which is normal and harmless. See how to find the page size of a PDF for the full routine.
Which A size for which job
- A4: letters, reports, invoices.
- A5 / A6: flyers, notebooks, postcards.
- A3 / A2: posters, drawings, presentations.
- A1 / A0: large drawings and technical plans.
Comparing with North American paper? Read US Letter vs A4.
Frequently asked questions
What is the size of A4 in mm?
A4 is 210 x 297 mm, which is 8.27 x 11.69 inches or 595.28 x 841.89 PDF points.
Why are A-series sizes based on the square root of 2?
A ratio of 1 : 1.4142 means that cutting a sheet in half across its long side gives two sheets with the same ratio, so every size scales perfectly to the next one.
How do I check if my PDF is A3 or A4?
Open it in PdfRuler and read the page width and height at the bottom right of the window. 297 x 420 mm is A3, 210 x 297 mm is A4.
