A Paper Sizes
A paper sizes are the ISO 216 series used for letters, reports and printed documents, running from A0 down to A10. A4 is the standard page size, and each size is half the area of the one above it.
A4 measures 210 millimetres wide and 297 millimetres tall.
The A Paper Sizes to Scale
Dimensions of All A Paper Sizes
The A Paper Sizes run from A0 at 841 × 1189 mm to A10 at 26 × 37 mm. Each size, with its closest US equivalent and typical use:
| Size | mm | cm | inches | Nearest US size | Common use |
|---|---|---|---|---|---|
| A0 | 841 × 1189 | 84.1 × 118.9 | 33.11 × 46.81 | None | Technical drawings, conference posters |
| A1 | 594 × 841 | 59.4 × 84.1 | 23.39 × 33.11 | None | Flip charts, large plans |
| A2 | 420 × 594 | 42.0 × 59.4 | 16.54 × 23.39 | None | Mid-size posters, wall calendars |
| A3 | 297 × 420 | 29.7 × 42.0 | 11.69 × 16.54 | Tabloid (approx) | Spreadsheets, double-page spreads |
| A4 | 210 × 297 | 21.0 × 29.7 | 8.27 × 11.69 | Letter (approx) | Office documents, letterhead |
| A5 | 148 × 210 | 14.8 × 21.0 | 5.83 × 8.27 | Half Letter (approx) | Booklets, notepads, flyers |
| A6 | 105 × 148 | 10.5 × 14.8 | 4.13 × 5.83 | None | Postcards, index cards |
| A7 | 74 × 105 | 7.4 × 10.5 | 2.91 × 4.13 | None | Pocket notes, event tickets |
| A8 | 52 × 74 | 5.2 × 7.4 | 2.05 × 2.91 | None | Playing-card scale, luggage tags |
| A9 | 37 × 52 | 3.7 × 5.2 | 1.46 × 2.05 | None | Small labels, price tags |
| A10 | 26 × 37 | 2.6 × 3.7 | 1.02 × 1.46 | None | Stamps, micro-labels |
Dimensions are portrait (short edge first), rounded to the nearest millimetre exactly as ISO 216 defines them. Centimetre, inch and pixel values are derived by formula, not separate standards.
The A Paper Sizes from Largest to Smallest
Line the A sizes up and each one is exactly half the last. A0 (841 × 1189 mm) folds to A1, A1 to A2, and so on: two A4 pages make an A3, two A3 make an A2, four A4 make an A2. That is why an A3 spreadsheet reduces onto A4 at 71 percent with nothing lost, and an A4 handout enlarges to A3 at 141 percent. In practice the sizes that get used are A4 for letters and reports, A3 for tables and posters that fold back to A4, A5 for booklets and flyers, and A2 upward for wall posters and plans.
What the A Paper Sizes Are in Inches
ISO 216 sets the A series in millimetres; the inch figures are conversions, rounded to two decimal places. A4 is 8.27 × 11.69 in, A3 is 11.69 × 16.54 in, A5 is 5.83 × 8.27 in, and A0 is 33.11 × 46.81 in. Not one of them lands on a round inch value, which is the clearest sign the series was designed around the metre. The table above lists all eleven A sizes from A0 to A10 already converted.
How the A Paper Size Series Is Built
A0 has an area of exactly one square metre and sides in the ratio 1 : √2. That ratio is the only one where cutting a rectangle in half across its long side gives two smaller rectangles of the same shape. Apply it again and again and you get A1, A2, A3 and so on, each half the area of the last.
A0 itself is defined as 2−1/4 m wide by 21/4 m tall, which works out to 841 × 1189 mm and an area of 0.999949 m². Each size after it is made by halving the longer side of the one above and rounding down to the nearest millimetre, which is why A4 comes out at 210 × 297 rather than a round 200 × 300.
Which A Paper Size Do You Need?
A4 for anything that goes through an office printer or a filing system. A3 when a table or a layout needs twice the width and can fold back to A4. A5 for booklets and order pads that post in a DL envelope after one fold. A2, A1 and A0 for posters, plans and drawings read from across a room. A6 is the postcard size; A7 and below are for tickets, tags and labels.
Frequently Asked Questions
What are the A paper sizes?
A0 through A10, defined by ISO 216. A0 is one square metre; each size after it is half the area of the one before. A4 (210 × 297 mm) is the common office size, followed by A5, A3 and A2.
Which A paper size is used the most?
A4. It is the default page size in nearly all countries except the United States, Canada and a few others, so it covers letters, invoices, contracts and printer trays worldwide.
Are A paper sizes used everywhere?
Almost. A4 is standard across Europe, Asia, Africa, Australia and South America. North America uses Letter instead, which is 6 mm wider and 18 mm shorter.
How do I convert an A paper size to inches?
Divide each millimetre figure by 25.4. A4 at 210 × 297 mm becomes 8.27 × 11.69 in. The table on this page lists each A size already converted.
Is A4 an official international standard?
Yes. A4 and the rest of the A series are set by ISO 216, first published in 1975 and since adopted as a national standard by more than 100 countries.
✓ Member dimensions per ISO 216:2007. Centimetre, inch and pixel values derived by formula. Last verified . Editorial Process →