A3 Paper Size in mm, Inches and Points
A3 is 297 x 420 mm (11.69 x 16.54 in, 842 x 1191 pt). Drawings, diagrams, large spreadsheets and small posters. Two A3 sheets side by side make an A2.
| Unit | Width | Height |
|---|---|---|
| Millimetres | 297 mm | 420 mm |
| Centimetres | 29.7 cm | 42 cm |
| Inches | 11.69 in | 16.54 in |
| Points (PDF) | 841.89 pt | 1190.55 pt |
| Pixels at 96 dpi | 1123 px | 1587 px |
The sides are in the ratio 1 : 1.414 (the square root of 2), which is why folding or cutting an A-series sheet in half keeps its shape. Area: 0.1247 m². Landscape: 420 x 297 mm.
A3 in pixels at different resolutions
| Resolution | Size |
|---|---|
| 72 dpi | 842 x 1191 px |
| 96 dpi | 1123 x 1587 px |
| 150 dpi | 1754 x 2480 px |
| 300 dpi | 3508 x 4961 px |
| 600 dpi | 7016 x 9921 px |
How to check a PDF really is A3
- Open the file in PdfRuler. It runs in your browser and nothing is uploaded.
- Read the page size in the status bar and set the unit to mm. It should read 297 x 420 mm.
- A PDF that says 842 x 1191 pt is the same sheet rounded to whole points, so mm may differ by a fraction. That is normal; see what a PDF point is.
Printing it? Check your printer does not rescale the page with the print at actual size test sheet.
Related sizes
- Next larger: A2 (420 x 594 mm), which has twice the area.
- Next smaller: A4 (210 x 297 mm), half the area.
Frequently asked questions
What is the size of A3 in mm?
A3 is 297 x 420 mm (11.69 x 16.54 in) in portrait.
How many pixels is A3?
At 96 dpi, the size of a CSS pixel on screen, A3 is 1123 x 1587 px. At 300 dpi, a common print resolution, it is 3508 x 4961 px.
What is A3 in points (the PDF unit)?
A3 is 841.89 x 1190.55 pt, usually rounded to 842 x 1191 pt. One point is 1/72 of an inch, and PDF page sizes are stored in points.
