A3 paper size and dimensions
A3 measures 297 × 420 mm, which is 29.7 × 42 cm or 11.69 × 16.54 inches. A3 is twice the size of A4: two A4 sheets side by side make exactly one A3 sheet.
Contents of this page
A3, portrait
297 × 420mm
- Centimetres
- 29.7 × 42 cm
- Inches
- 11.69 × 16.54 in
- Pixels at 300 dpi
- 3508 × 4961 px
- Points (pt)
- 842 × 1191 pt
- Area
- 0.1247 m²
- Weight at 80 gsm
- 9.98 g
The short side of A3 is exactly as long as the long side of A4. That makes A3 the natural size for anything that shows a spread: an open brochure, a spreadsheet with lots of columns, drawings and printed presentation slides.
A3 in every unit
| Unit | Width × height |
|---|---|
| Millimetres | 297 × 420 mm |
| Centimetres | 29.7 × 42 cm |
| Metres | 0.297 × 0.42 m |
| Inches | 11.69 × 16.54 in |
| DTP points (1/72 in) | 842 × 1191 pt |
| Area | 1247.4 cm², or 0.1247 m² |
| Diagonal | 514.4 mm |
| Aspect ratio | 1 : 1.414 |
A3 in pixels
For print at 300 dpi an A3 image needs 3508 × 4961 pixels, a little over 17 megapixels. A 24-megapixel camera covers that comfortably. A 12-megapixel phone photo (4032 × 3024) reaches about 245 dpi, which still prints well as long as you do not crop much.
| Resolution | Pixels | Megapixels | Good for |
|---|---|---|---|
| 72 dpi | 842 × 1191 px | 1 MP | Screen, preview |
| 96 dpi | 1123 × 1587 px | 1.8 MP | Screen (Windows default) |
| 150 dpi | 1754 × 2480 px | 4.3 MP | Large format, posters seen from a distance |
| 300 dpi | 3508 × 4961 px | 17.4 MP | Offset and digital print |
| 600 dpi | 7016 × 9921 px | 69.6 MP | Line art, fine detail |
What A3 is used for
- Technical drawings and small-scale plans
- Spreadsheets and charts that are too cramped on A4
- Small posters, notices and menus
- Print sheets for A4 brochures: one A3 sheet folded in the middle gives four A4 pages
- Drawing pads and sketchbooks
Printing and copying A3
Many office printers cannot do A3. If the box says “A3”, read the small print: some inkjets only take A3 through a single-sheet feed and print it on one side only. Office multifunction devices usually handle it as standard.
For copying, use the two ISO factors: 141 % from A4 to A3 and 71 % from A3 to A4. Because both sizes share the same aspect ratio, nothing is left over and nothing is cut off.
A3 vs Tabloid
The closest American size is Tabloid (called Ledger when landscape) at 11 × 17 inches, which is 279.4 × 431.8 mm. It is almost 18 mm narrower and 12 mm longer than A3. If you send an A3 file to a US printer, expect margins or adapt the file to Tabloid first.
Which envelope fits A3?
Flat, A3 fits a C3 envelope (324 × 458 mm). Most people fold it once to A4 and use a C4 envelope. Plans that must not be creased go into a postal tube.
Frequently asked questions
How big is A3 in cm?
A3 is 29.7 cm wide and 42 cm tall.
How big is A3 in inches?
11.69 × 16.54 inches.
Is A3 twice the size of A4?
Yes. A3 has exactly twice the area of A4.
What percentage is A4 to A3?
141 %. The other way, A3 to A4, is 71 %.
Is A3 the same as Tabloid?
No. Tabloid is 279.4 × 431.8 mm, narrower and slightly longer than A3 at 297 × 420 mm.