Quick answer: A4 paper measures 210 x 297 mm, which is 8.3 x 11.7 inches (21 x 29.7 cm). The full chart below converts every A series paper size — A0 through A10 — into millimetres, centimetres and inches.
A sizes are part of the ISO 216 standard used internationally to describe paper sizes. The main exception is North America and parts of Central and South America, which use sizes such as "Letter" and "Legal" based on the imperial measurement system — see how they compare to A sizes below.
A paper sizes chart: mm, cm and inches
All measurements are width x height (portrait orientation).
| Size | Millimetres (mm) | Centimetres (cm) | Inches (in) |
| A0 | 841 x 1189 mm | 84.1 x 118.9 cm | 33.1 x 46.8 in |
| A1 | 594 x 841 mm | 59.4 x 84.1 cm | 23.4 x 33.1 in |
| A2 | 420 x 594 mm | 42 x 59.4 cm | 16.5 x 23.4 in |
| A3 | 297 x 420 mm | 29.7 x 42 cm | 11.7 x 16.5 in |
| A4 | 210 x 297 mm | 21 x 29.7 cm | 8.3 x 11.7 in |
| A5 | 148 x 210 mm | 14.8 x 21 cm | 5.8 x 8.3 in |
| A6 | 105 x 148 mm | 10.5 x 14.8 cm | 4.1 x 5.8 in |
| A7 | 74 x 105 mm | 7.4 x 10.5 cm | 2.9 x 4.1 in |
| A8 | 52 x 74 mm | 5.2 x 7.4 cm | 2.0 x 2.9 in |
| A9 | 37 x 52 mm | 3.7 x 5.2 cm | 1.5 x 2.0 in |
| A10 | 26 x 37 mm | 2.6 x 3.7 cm | 1.0 x 1.5 in |
The most common A sizes explained
A4 — 210 x 297 mm (8.3 x 11.7 in)
The everyday standard for documents, certificates and small prints across most of the world. If you're framing something A4 sized, see our A4 picture frames.
A3 — 297 x 420 mm (11.7 x 16.5 in)
Twice the area of A4 — a popular size for small posters, art prints and photography. Browse A3 frames.
A2 — 420 x 594 mm (16.5 x 23.4 in)
A common mid-size poster and print format that reads well on a wall without dominating it. Browse A2 frames.
A1 — 594 x 841 mm (23.4 x 33.1 in)
A large statement size used for posters, maps and architectural drawings. Browse A1 frames.
A0 — 841 x 1189 mm (33.1 x 46.8 in)
The largest standard A size — exactly one square metre of paper. Browse A0 frames.
How A paper sizes work
Every A size is exactly half the size above it: cut a sheet in half across its longest side and you get two sheets of the next size down. One A3 sheet (297 x 420 mm) cut in half gives two A4 sheets (210 x 297 mm).
Going the other way, the next size up takes the longer side as its new shorter side, and doubles the old shorter side. From A4 (210 x 297 mm): the new width is 297 mm and the new height is 210 x 2 = 420 mm, giving A3 at 297 x 420 mm. Because every size shares the same width-to-height ratio (1:√2), artwork scales between A sizes without cropping.
In design and print, measurements are written width x height — the same as the x and y coordinates of a graph. The image below shows how each A size relates to its neighbour: half the longest side matches the shortest side of the size below.
There are also A sizes larger than A0, indicated with a multiplier before the A0 — 2A0 (double A0), then 4A0, and so on. These aren't part of the ISO 216 standard itself but developed to cover larger formats that have become common.
A sizes vs US Letter and Legal
North American paper sizes don't line up exactly with the A series. The closest match is Letter to A4 — Letter is slightly wider and shorter:
| US size | Inches | Millimetres | Nearest A size |
| Letter | 8.5 x 11 in | 216 x 279 mm | A4 (210 x 297 mm) |
| Legal | 8.5 x 14 in | 216 x 356 mm | A4 (210 x 297 mm) |
| Tabloid | 11 x 17 in | 279 x 432 mm | A3 (297 x 420 mm) |
A sizes and framing
ISO 216 allows small production tolerances: ±1.5 mm for dimensions up to 150 mm, and ±2 mm for lengths between 150 and 600 mm. This matters for framing — a frame should allow for this so the print fits without being too loose or too tight. All of our picture frames are cut to order, so an A size print (or any custom size) fits exactly. You can also print your own photo or artwork at any A size, with or without a frame.
Frequently asked questions
What is 210 x 297 mm in inches?
210 x 297 mm is 8.3 x 11.7 inches — this is A4 paper.
Is A4 the same as US Letter?
No. A4 (8.3 x 11.7 in) is slightly narrower and taller than Letter (8.5 x 11 in). Documents laid out for one often need margin adjustments to print on the other.
What is 420 x 594 mm in inches?
420 x 594 mm is 16.5 x 23.4 inches — this is A2 paper.
What size frame do I need for an A size print?
Use a frame made for that exact A size — for example an A4 frame for a 210 x 297 mm print. A made-to-measure frame avoids relying on off-the-shelf sizes that may not allow for paper tolerance.