Convert poster dimensions and find out how many sheets you need to print them at home.
Pick a paper size and a grid to see the finished poster size, or choose a target such as A3, A2 or 24 × 36 inches to get the fewest sheets that cover it. Below you will also find the A3 poster size in centimetres, inches and pixels, plus a chart of every standard format. Every figure accounts for the 10 mm margin home printers need.
An A3 poster measures 297 × 420 mm — 29.7 × 42 cm, or about 11.7 × 16.5 inches. It is exactly twice the area of an A4 sheet and half the area of A2, with the same 1 : √2 proportions as every A-series size, so artwork scales between them without cropping.
To print a sharp A3 poster at 300 DPI you need an image of at least 3508 × 4961 pixels; 150 DPI (1754 × 2480 px) is fine for viewing from a metre or more. No A3 printer? Four A4 sheets in a 2 × 2 grid cover a full A3 poster with room to spare.
The A3 poster size is popular because frames are cheap and easy to find, many office copiers take A3 paper directly, and it is large enough to read across a desk or a corridor noticeboard. A landscape A3 poster is simply the same sheet turned sideways: 420 × 297 mm, or 16.5 × 11.7 inches.
| Measure | A3 |
|---|---|
| Millimetres | 297 × 420 mm |
| Centimetres | 29.7 × 42 cm |
| Inches | 11.7 × 16.5 in |
| Pixels @ 300 DPI | 3508 × 4961 px |
| Pixels @ 150 DPI | 1754 × 2480 px |
| Print at home on A4 | 4 sheets (2 × 2), covers 38 × 55 cm (15.0 × 21.8 in) |
ISO and US poster formats with the sheets needed to print each one at home (10 mm margin, best sheet orientation chosen automatically).
| Size | Millimetres | Inches | Pixels @ 300 DPI | A4 sheets | Letter sheets |
|---|---|---|---|---|---|
| A0 | 841 × 1189 | 33.1 × 46.8 | 9933 × 14043 | 25 | 25 |
| A1 | 594 × 841 | 23.4 × 33.1 | 7016 × 9933 | 15 | 15 |
| A2 | 420 × 594 | 16.5 × 23.4 | 4961 × 7016 | 8 | 8 |
| A3 | 297 × 420 | 11.7 × 16.5 | 3508 × 4961 | 4 | 4 |
| A4 | 210 × 297 | 8.3 × 11.7 | 2480 × 3508 | 2 | 2 |
| 11 × 17" | 279.4 × 431.8 | 11.0 × 17.0 | 3300 × 5100 | 4 | 4 |
| 18 × 24" | 457.2 × 609.6 | 18.0 × 24.0 | 5400 × 7200 | 8 | 8 |
| 24 × 36" | 609.6 × 914.4 | 24.0 × 36.0 | 7200 × 10800 | 15 | 15 |
| 27 × 40" | 685.8 × 1016 | 27.0 × 40.0 | 8100 × 12000 | 16 | 16 |
ISO 216 sizes start from A0, a sheet of one square metre. Each smaller size halves the previous one along its long side: A1 is half of A0, A2 half of A1, and so on. Because the ratio of the sides is always 1 : √2, an A4 design enlarges to A3, A2 or A0 without distortion.
In the United States posters are sold in inches: 11 × 17 (tabloid), 18 × 24, 24 × 36 and the 27 × 40 one-sheet used for film posters. Their proportions differ from the A series, so an A-series design printed at a US size gains a little border or loses a little edge.
A3 and 11 × 17 suit notices and small wall art. A2 and 18 × 24 are the classic bedroom and office poster. A1, A0, 24 × 36 and 27 × 40 make a statement piece that needs a big wall — and a high-resolution image or a halftone effect.
Once you know the size, upload your photo to our Image to Poster tool to split it into print-ready pages with crop marks, or use the block poster maker for a grid-style wall piece. Both are free and run entirely in your browser.
A3 is 29.7 × 42 cm (297 × 420 mm), which is approximately 11.7 × 16.5 inches.
3508 × 4961 pixels for 300 DPI print quality, or 1754 × 2480 pixels at 150 DPI, which is enough for viewing from about a metre away.
Allowing for the printer margin, a full A3 poster needs 4 A4 sheets, A2 needs 8, A1 needs 15 and A0 needs 25. The chart above lists every size for A4 and US Letter paper.
Close, but not identical. A3 is 11.7 × 16.5 inches, so it is slightly wider and slightly shorter than 11 × 17 (tabloid).
The US one-sheet is 27 × 40 inches (68.6 × 101.6 cm). Smaller reprints are often sold at 24 × 36 inches.
Most home printers cannot print to the edge of the page, so each sheet keeps a 10 mm border that is trimmed away. The calculator uses only the printable area, so the finished size is what you will really get.
An A3 poster is exactly twice the area of an A4 sheet (210 × 297 mm, or 8.3 × 11.7 inches). Its short side, 297 mm, equals the long side of A4, so two A4 pages laid side by side along their long edges make one A3 sheet.
A2 is 420 × 594 mm (16.5 × 23.4 in), A1 is 594 × 841 mm (23.4 × 33.1 in) and A0 is 841 × 1189 mm (33.1 × 46.8 in). Each size has double the area of the one below it, so an A1 poster covers the same area as four A3 posters.
11 × 17 in is 27.9 × 43.2 cm, 18 × 24 in is 45.7 × 61 cm, 24 × 36 in is 61 × 91.4 cm and the 27 × 40 in movie one-sheet is 68.6 × 101.6 cm. The closest A-series match for 18 × 24 is A2, and for 24 × 36 it is A1, although both US sizes are a little larger.
The farther away people stand, the bigger the poster needs to be. An A3 poster reads well at arm's length on a desk, door or noticeboard; A2 or 18 × 24 inches suits a bedroom wall seen from two or three metres; A1, A0 or 24 × 36 inches holds its own in a living room, hallway or event space.
Viewers standing farther away cannot see fine pixels, so larger posters need less density. Use 300 DPI for A3 and smaller prints examined up close and 150 DPI for A2 and A1 on a wall; A0 seen from a few metres often looks fine at 100 DPI. At 150 DPI an A1 poster needs about 3508 × 4967 pixels.