Quick answer: The most widely used international system is ISO 216. Its A series runs from A0 at 841 × 1189 mm to A10 at 26 × 37 mm. The B series provides intermediate and larger formats, while C sizes are principally associated with envelopes.
This chart brings the main international and North American paper formats into one place. The dimensions are finished sheet sizes, stated width × height in portrait orientation. For print production, allow separately for bleed, crop marks, folding, binding and the tolerances specified by the printer.
Measurement note: dimensions are stated width × height in portrait orientation. Turn the sheet through 90 degrees for landscape use. Millimetres are the controlling values for ISO sizes; inch figures are rounded conversions.
ISO A, B and C paper size 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 × 59.4 cm | 16.54 × 23.39 in |
| A3 | 297 × 420 mm | 29.7 × 42 cm | 11.69 × 16.54 in |
| A4 | 210 × 297 mm | 21 × 29.7 cm | 8.27 × 11.69 in |
| A5 | 148 × 210 mm | 14.8 × 21 cm | 5.83 × 8.27 in |
| A6 | 105 × 148 mm | 10.5 × 14.8 cm | 4.13 × 5.83 in |
| A7 | 74 × 105 mm | 7.4 × 10.5 cm | 2.91 × 4.13 in |
| A8 | 52 × 74 mm | 5.2 × 7.4 cm | 2.05 × 2.91 in |
| A9 | 37 × 52 mm | 3.7 × 5.2 cm | 1.46 × 2.05 in |
| A10 | 26 × 37 mm | 2.6 × 3.7 cm | 1.02 × 1.46 in |
| B0 | 1000 × 1414 mm | 100 × 141.4 cm | 39.37 × 55.67 in |
| B1 | 707 × 1000 mm | 70.7 × 100 cm | 27.83 × 39.37 in |
| B2 | 500 × 707 mm | 50 × 70.7 cm | 19.69 × 27.83 in |
| B3 | 353 × 500 mm | 35.3 × 50 cm | 13.90 × 19.69 in |
| B4 | 250 × 353 mm | 25 × 35.3 cm | 9.84 × 13.90 in |
| B5 | 176 × 250 mm | 17.6 × 25 cm | 6.93 × 9.84 in |
| B6 | 125 × 176 mm | 12.5 × 17.6 cm | 4.92 × 6.93 in |
| B7 | 88 × 125 mm | 8.8 × 12.5 cm | 3.46 × 4.92 in |
| B8 | 62 × 88 mm | 6.2 × 8.8 cm | 2.44 × 3.46 in |
| B9 | 44 × 62 mm | 4.4 × 6.2 cm | 1.73 × 2.44 in |
| B10 | 31 × 44 mm | 3.1 × 4.4 cm | 1.22 × 1.73 in |
| C0 | 917 × 1297 mm | 91.7 × 129.7 cm | 36.10 × 51.06 in |
| C1 | 648 × 917 mm | 64.8 × 91.7 cm | 25.51 × 36.10 in |
| C2 | 458 × 648 mm | 45.8 × 64.8 cm | 18.03 × 25.51 in |
| C3 | 324 × 458 mm | 32.4 × 45.8 cm | 12.76 × 18.03 in |
| C4 | 229 × 324 mm | 22.9 × 32.4 cm | 9.02 × 12.76 in |
| C5 | 162 × 229 mm | 16.2 × 22.9 cm | 6.38 × 9.02 in |
| C6 | 114 × 162 mm | 11.4 × 16.2 cm | 4.49 × 6.38 in |
| C7 | 81 × 114 mm | 8.1 × 11.4 cm | 3.19 × 4.49 in |
| C8 | 57 × 81 mm | 5.7 × 8.1 cm | 2.24 × 3.19 in |
| C9 | 40 × 57 mm | 4 × 5.7 cm | 1.57 × 2.24 in |
| C10 | 28 × 40 mm | 2.8 × 4 cm | 1.10 × 1.57 in |
Common North American sizes
| Name | Inches | Millimetres | Typical use |
|---|---|---|---|
| Letter | 8.5 × 11 in | 215.9 × 279.4 mm | Office documents and correspondence |
| Legal | 8.5 × 14 in | 215.9 × 355.6 mm | Contracts and long forms |
| Tabloid / Ledger | 11 × 17 in | 279.4 × 431.8 mm | Newsletters, drawings and spreads |
| Executive | 7.25 × 10.5 in | 184.2 × 266.7 mm | Compact business stationery |
| Half Letter / Statement | 5.5 × 8.5 in | 139.7 × 215.9 mm | Booklets, organisers and statements |
| Junior Legal | 5 × 8 in | 127 × 203.2 mm | Notepads and compact forms |
How to choose the correct size
Start with the physical task, not the design software. Ask whether the item must fit a printer tray, envelope, filing system, display frame, postal category, book-production platform or reader’s hand. A4 and US Letter are close but not interchangeable: an A4 design printed on Letter can lose content at the top and bottom, while a Letter design printed on A4 may gain narrow side margins.
- For everyday international office work, begin with A4.
- For North American office work, see US Letter.
- For envelopes, use the C-series guide and check postal limits.
- For commercial printing with bleed, see RA and SRA sizes.
- For books, posters, cards and other products, use the dedicated application guides rather than assuming that one universal standard exists.
Why inch conversions vary slightly
ISO sizes are defined in millimetres. When converted to inches, the result is usually rounded to two decimal places. A specification written as 8.27 × 11.69 inches therefore describes A4 approximately; 210 × 297 mm is the exact nominal size. Never rebuild an ISO layout from a rounded inch value when millimetres are available.
Printing and scaling rule
All A-series sheets share the 1:√2 aspect ratio. This means an A4 page can be enlarged to A3 at approximately 141.4%, or reduced to A5 at approximately 70.7%, without changing its proportions. B-series dimensions also follow the same aspect ratio, but B sizes are not simply halves of A sizes. C envelopes are dimensioned to accept corresponding A-series contents with practical clearance.
Frequently asked questions
What is the standard paper size in the UK?
A4, measuring 210 × 297 mm, is the normal office and home-printer size in the United Kingdom.
What is the standard paper size in the United States?
US Letter, measuring 8.5 × 11 inches, is the usual office format. Legal and Tabloid/Ledger are also common.
Are poster and book sizes standardised?
Some posters use A-series sizes, but many advertising and photographic formats are customary rather than universal. Books are produced in numerous trim sizes chosen by market, genre, binding and printer capability.
Sources and standards
The measurements and production guidance in this guide were checked against the following standards bodies, postal operators and print-platform specifications. Standards can be revised or withdrawn, so check the linked record when a contractual or regulated specification matters.