Which is bigger A1 A2 or A3?
A1 is the biggest of the three: A1 is twice the area of A2, and A2 is twice the area of A3. In full — A1 is 594 × 841 mm, A2 is 420 × 594 mm, and A3 is 297 × 420 mm.
The numbering runs backwards from what people expect: the smaller the number, the bigger the sheet. A0 is the largest, A10 the smallest. That is the single thing that makes the A series confusing, and once you know it the rest follows.
A1 vs A2 vs A3, side by side
| Size | Millimetres | Centimetres | Inches | Compared with |
|---|---|---|---|---|
| A1 | 594 × 841 mm | 59.4 × 84.1 cm | 23.39 × 33.11 in | Twice A2. Half A0 |
| A2 | 420 × 594 mm | 42.0 × 59.4 cm | 16.54 × 23.39 in | Twice A3. Half A1 |
| A3 | 297 × 420 mm | 29.7 × 42.0 cm | 11.69 × 16.54 in | Twice A4. Half A2 |
So an A1 sheet is four times the area of an A3, not one and a half times — which is the mistake people make when they are choosing a poster size from a number rather than looking at it.
How the doubling works
Each size is the one above it folded in half along its long edge. A4's short edge, 210 mm, becomes A3's long edge, 420 mm. A3's short edge, 297 mm, becomes A2's long edge, 594 mm. And so on up to A0.
Because the fold always works the same way, the proportions never change — the ratio of every A size is 1 : √2. That is why you can scale artwork from A3 to A1 and nothing gets cropped or stretched.
A0 is exactly one square metre, which is where the whole series starts. It is also why paper weight is quoted in gsm — grams per square metre — so a sheet of A0 in 80gsm paper weighs exactly 80 grams.
The full A-series chart
| Size | Millimetres | Centimetres | Inches |
|---|---|---|---|
| A0 | 841 × 1189 mm | 84.1 × 118.9 cm | 33.11 × 46.81 in |
| A1 | 594 × 841 mm | 59.4 × 84.1 cm | 23.39 × 33.11 in |
| A2 | 420 × 594 mm | 42.0 × 59.4 cm | 16.54 × 23.39 in |
| A3 | 297 × 420 mm | 29.7 × 42.0 cm | 11.69 × 16.54 in |
| A4 | 210 × 297 mm | 21.0 × 29.7 cm | 8.27 × 11.69 in |
| A5 | 148 × 210 mm | 14.8 × 21.0 cm | 5.83 × 8.27 in |
| A6 | 105 × 148 mm | 10.5 × 14.8 cm | 4.13 × 5.83 in |
Which one should you actually use?
Work back from how far away it is read, not from the number.
| Size | Read from | Typical use |
|---|---|---|
| A1 | 3–5 m | Shop windows, event posters, seating charts, exhibition boards |
| A2 | 2–3 m | Wall menus, notice boards, real estate window cards |
| A3 | 1–2 m | Counter signage, table menus, school notices, certificates |
The lettering rule that settles it
Most people choosing between A1, A2 and A3 are really asking whether the thing will be readable. The working rule is about 25 mm of capital letter height for every metre of viewing distance.
| Read from | Minimum cap height | Fits comfortably on |
|---|---|---|
| 1 m | 25 mm | A4, A3 |
| 3 m | 75 mm | A2, A1 |
| 5 m | 125 mm | A1, A0 |
| 10 m | 250 mm | A0 and larger, or a banner |
A headline that fails this rule on an A2 does not get fixed by moving up to A1 — it gets fixed by using fewer words.
Printing at these sizes
Paper is fine indoors and behind glass. Outdoors — on a gate, a fence or a shop window in the sun — it does not last a week. Our standard corflute sign is 600 × 900 mm, within a few millimetres of A1, and it is waterproof and rigid. For something that stands up by itself at an entrance, a pull up banner is 800 × 2000 mm. For a footpath, an A-frame sign takes a replaceable insert. Past A0, a printed sheet stops being practical and fabric or vinyl banners are what scale.
Everything is printed in our own factory in Derrimut, Melbourne and dispatched within 24 hours of proof approval. You can add your own wording to a ready-made design online for free, or send print-ready artwork. Custom sizing is available if none of the standard sizes fit.
Related: A1 size in cm · A5 size in cm · Is A3 bigger than A4? · Common poster sizes in Australia
