A3 Paper Size in mm, cm & Inches
A3 is twice the area of A4 — the standard paper size for posters, architectural plans, and large-format printing. It is defined by the ISO 216 international standard and used worldwide.
Proportional size comparison — A2 = 2× A3, A3 = 2× A4
ISO A-Series & US Paper Sizes
| Size | mm | cm | inches | px @ 96ppi |
|---|---|---|---|---|
| A1 | 594 × 841 | 59.4 × 84.1 | 23.39 × 33.11 | 2245 × 3179 |
| A2 | 420 × 594 | 42.0 × 59.4 | 16.54 × 23.39 | 1587 × 2245 |
| A3 | 297 × 420 | 29.7 × 42.0 | 11.69 × 16.54 | 1123 × 1587 |
| A4 | 210 × 297 | 21.0 × 29.7 | 8.27 × 11.69 | 794 × 1123 |
| A5 | 148 × 210 | 14.8 × 21.0 | 5.83 × 8.27 | 559 × 794 |
| US Tabloid | 279 × 432 | 27.9 × 43.2 | 11.0 × 17.0 | 1056 × 1632 |
| US Letter | 216 × 279 | 21.6 × 27.9 | 8.5 × 11.0 | 816 × 1056 |
A3 in Pixels at Different DPI
| Resolution | Width (px) | Height (px) |
|---|---|---|
| 72 DPI (PDF legacy) | 842 | 1191 |
| 96 PPI (web / screen) | 1123 | 1587 |
| 150 DPI (medium print) | 1754 | 2480 |
| 300 DPI (high-res print) | 3508 | 4961 |
Frequently Asked Questions
What is A3 paper size in mm?
A3 paper is 297 mm wide and 420 mm tall. It is exactly twice the area of A4 paper (210 × 297 mm). Fold an A3 sheet in half and you get exactly A4.
What is A3 paper size in inches?
A3 paper is 11.69 inches wide and 16.54 inches tall. This makes it slightly larger than US Tabloid (11 × 17 in). A3 is commonly used for posters, drawings, and large-format printing.
What is A3 in cm?
A3 paper is 29.7 cm wide and 42.0 cm tall. It is defined by the ISO 216 international standard, which specifies that all A-series sheets share a 1:√2 (approximately 1:1.414) aspect ratio.
How many pixels is A3 at 300 DPI?
At 300 DPI (the standard for high-quality printing), A3 is 3508 × 4961 pixels. At 96 PPI (web/screen standard), it is 1123 × 1587 pixels. At 72 DPI (legacy PDF), it is 842 × 1191 pixels.
What is A3 paper used for?
A3 is used for posters, architectural drawings, large spreadsheets, leaflets/brochures that fold to A4, engineering diagrams, and artwork. Most office printers cannot print A3 — you need an A3-capable printer or a print shop.
Is A3 the same as Tabloid?
No — they are close but not the same. A3 is 297 × 420 mm (11.69 × 16.54 in). US Tabloid (also called Ledger) is 279 × 432 mm (11 × 17 in). Tabloid is slightly narrower and taller than A3.