A4 vs Letter: size difference and how to print
A4 is narrower and taller than Letter. The difference is 5.9 mm in width and 17.6 mm in height, enough to cut off text when a file is printed on the wrong paper.
Last updated: September 28, 2026
A4 and Letter side by side
| Size | Width (mm) | Height (mm) | Width (in) | Height (in) |
|---|---|---|---|---|
| A4 | 210.0 | 297.0 | 8.27 | 11.69 |
| Letter | 215.9 | 279.4 | 8.50 | 11.00 |
Where each size is used
A4 belongs to the international A series and is the ordinary sheet in most of the world. Letter is the ordinary sheet in the United States and Canada.
Software gives a practical picture. The locale data that operating systems and applications use sets Letter as the default paper for the United States, Canada, Mexico, Puerto Rico, the Philippines, Chile, Colombia, Venezuela, Belize, Costa Rica, El Salvador, Guatemala, Nicaragua and Panama, and A4 everywhere else. These are software defaults, not laws: some of these countries have formally adopted the international sizes.
How to print one size on the other
- Open the print dialog and check which paper size the file expects and which paper is in the printer.
- Choose the option that fits the page to the paper. Its name differs between programs: fit, scale to fit or shrink to printable area.
- Look at the preview. Check that page numbers and footers are inside the sheet.
Printing a Letter page on A4 needs about 97 percent, because the page has to become narrower. Printing an A4 page on Letter needs about 94 percent, because the page has to become shorter.
If you create a document for readers in both regions, keep text and page numbers inside an area of 210 mm by 279.4 mm. That area fits both sheets.
Worked example: how the numbers are derived
A4 is defined in millimetres: 210 by 297. Letter is defined in inches: 8.5 by 11. One inch is exactly 25.4 mm, so Letter is exactly 215.9 mm by 279.4 mm, and A4 is about 8.27 by 11.69 inches.
Width: 215.9 minus 210 is 5.9 mm. Height: 297 minus 279.4 is 17.6 mm.
Scale for Letter on A4: 210 divided by 215.9 is 0.973. Scale for A4 on Letter: 279.4 divided by 297 is 0.941.
Common mistakes
- Printing at 100 percent on the other size. Either the sides or the bottom of the page are lost.
- Buying binders, sheet protectors or frames across regions without checking. An A4 sheet is too tall for a Letter binder.
- Designing to the edge of one size. Leave margins that survive on both.
- Calling A4 8.5 by 11. That is Letter.
Sources and checks
The values in the chart are calculated from the definitions in the sources below. They are not copied from another chart. Last checked against the sources on September 28, 2026.
A4 is 210 mm by 297 mm by definition; Letter is 8.5 in by 11 in by definition. The other two values of each row are conversions at 25.4 mm per inch.
Used for: Halving principle, side ratio of 1 to the square root of 2, A0 area of one square metre, B sizes as geometric means, and the millimetre values of A0 to A10 and B0 to B10 used to check the calculation.
Used for: Dimensions of North American, engineering, architectural, ISO C, envelope and JIS B sizes as used by printers and print software.
Used for: The territories where software defaults to Letter instead of A4. These are software defaults, not national law.
Frequently asked questions
- Is A4 bigger than Letter?
- A4 is taller and Letter is wider. By area A4 is slightly larger: 623.7 square centimetres compared with 603.2 square centimetres for Letter.
- Can I use A4 paper in a printer made for Letter?
- Check the manual. If the printer lists A4 among its paper sizes, move the paper guides and select A4 in the printer settings and in the print dialog.
- What is A4 in inches?
- A4 is 210 mm by 297 mm, which is about 8.27 by 11.69 inches.
- What is Letter in centimetres?
- Letter is 21.59 cm by 27.94 cm: 8.5 by 11 inches converted at exactly 2.54 cm per inch.
- Which size should I use for a document I send abroad?
- Use the size of the reader if you know it. If you do not, keep all content inside 210 mm by 279.4 mm, so the page prints on both A4 and Letter without loss.