Letter Size vs A4: Comparing Dimensions and Fixing Prints of Overseas Documents

Letter size and A4 differ by only a few millimetres each way, but in print the difference shows. Letter is the wider paper, and A4 is the taller one.

A4 is a standard paper used in many countries around the world (ISO 216). Letter is an inch-based paper used in the United States and Canada.

People tend to treat them as "about the same" whichever one a document is made in. If you print as is, the following happens.

• The lines at the bottom get cut off
• The left and right margins shift
• The whole page is slightly reduced

The key point: knowing the difference in numbers tells you what to fix before you print.

This article covers the following.

• The dimensional difference between Letter size and A4 (mm, inches, pixels)
• The countries that use Letter size, and similar North American papers
• What happens when you print documents from overseas
• How to fix it in Word, Excel, PDF and printer settings
• How to work out safe margins that print on both papers

The dimensions are shown in tables based on the standards.

Conclusion: what is the difference between Letter size and A4?

Letter size is wider and shorter than A4. A4 has a slightly larger area.

Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1

Working out the difference from the values in the table gives the following.

• Width: 215.9 − 210 = 5.9mm (Letter is wider)
• Height: 297 − 279.4 = 17.6mm (A4 is taller)
• Area: A4 is 62,370mm², Letter is about 60,322mm²

A4 has about 3.4% more area. Some explanations say "Letter is larger", but by calculation A4 comes out ahead.

Letter wins on width and A4 wins on height, so whichever paper you print on, one side will not fit.

Legal in the table is a North American paper with the same width as Letter but a longer height.

How does the difference between Letter and A4 look in a diagram?

As the diagram shows, Letter is wider and stubbier than A4. Comparing the aspect ratios makes the difference clear.

• A4: 297 ÷ 210 ≈ 1.414 (1 : √2)
• Letter: 279.4 ÷ 215.9 ≈ 1.294

Because the ratios differ, enlarging or reducing alone never makes them line up exactly. A margin always remains in one direction.

How can you check the difference between Letter and A4 with a calculator?

Select Letter and A4 in the tool above to see mm, inches and pixels side by side. You can also get the enlargement or reduction ratio.

The tool runs entirely in your browser, and the values you enter are not sent anywhere. The ratio uses the smaller of the width and height values.

Where is Letter size used?

Letter size is used in the United States and Canada for everyday documents and copy paper. It is the paper that plays the role A4 plays in Japan.

The US drawing standard (ASME Y14.1) calls the size equal to Letter "A size". The 11 × 17 inch size, equal to Tabloid, is "B size".

Besides Letter, North America has the following papers.

Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1

Note that the names "A" and "B" are not the same as Japan's A and B series. If a drawing is said to be "A size", in North America that means the size of Letter.

Japanese printers and software also list "Letter" among their paper sizes. However, few shops actually stock Letter paper itself.

What happens with overseas documents because of the difference between Letter and A4?

Three things happen: pages get cut off, margins shift, or pages shrink. Which one depends on the print settings.

The numbers in the table come from these calculations.

• Top and bottom difference: (297 − 279.4) ÷ 2 = 8.8mm
• Left and right difference: (215.9 − 210) ÷ 2 ≈ 3mm
• A4 → Letter: 279.4 ÷ 297 ≈ 94.1%
• Letter → A4: 210 ÷ 215.9 ≈ 97.3%

The hardest one to notice is shrinking. At 94%, 10.5-point text becomes about 9.9 points. It is still readable, but it causes trouble with forms that have fixed dimensions.

Whether the page is centred or aligned to the top depends on the software and printer. Before printing, check the bottom edge in the print preview.

Why does it shrink when you did not ask it to?

Because the software or printer is set to enlarge or reduce automatically to fit the paper.

PDF viewers and the Mac print dialog have a "fit to paper" option. If it is selected, the page is shrunk to bridge the difference between Letter and A4.

Word also has a setting that automatically scales content between A4 and Letter. If you want to stop the shrinking, first check that the scale is set to 100%.

Why does it say "paper size does not match"?

Because the paper loaded in the printer differs from the paper specified in the data.

Epson's FAQ advises matching the two papers: the paper selected in the software and the paper set on the printer's control panel.

This message tends to appear when A4 paper is loaded but the data is still set to Letter.

How do you fix the difference between Letter and A4 in Word and Excel?

In Word and Excel, change the document's paper size to match the paper you print on. Where to set it is shown in the table below.

Microsoft Support gives this warning for Excel: if the settings and the paper in the printer differ, the printout may not match the preview.

Before sending a document, the safe approach is to switch it to the paper used in the recipient's country and review the page breaks.

What shifts when you change the paper size in Word?

The number of lines that fit on a page changes. Changing from A4 to Letter makes the page shorter, so lines spill over.

Tables and figures may move to the next page and leave blank space. After changing the paper, check every page by eye, all the way to the last.

Besides the standard sizes, Word's paper size list has a "Custom size" option. You can enter the width and height in mm to make any size you like.

How do you fix the difference between Letter and A4 when printing a PDF?

For PDFs, choose how the page fits the paper under "Page Sizing & Handling" in Acrobat. There are four options.

The same screen also has a checkbox, "Choose paper source by PDF page size". If it is on, the printer may stop while looking for Letter paper.

If you only print on A4 paper, clear this checkbox. Then choose "Fit" or "Shrink oversized pages".

The Mac print dialog has "Scale to fit paper size". It lets you print on paper of a different size from the one the document was made in.

How do you fix the difference between Letter and A4 on the printer side?

In the printer driver (the print settings screen), choose the document size and the size of the paper you print on separately.

Here is an example for a Canon driver.

1. Under "Document Size", choose the size of the data (Letter)
2. Under "Output Paper Size", choose the paper you actually loaded (A4)
3. The ratio is set automatically. To set it yourself, tick "Specify Scaling"

If scaling is also set in the software, that setting may take priority. To avoid applying a ratio twice, set it in one place only.

On Epson printers, also match the paper setting on the printer's control panel to the data. Setting names differ by model, so check the manual.

What margins are safe when you make a document in A4 and print it on Letter?

The area that fits on both sheets is a rectangle as wide as A4 and as tall as Letter. Keep text and tables inside this area.

Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1

From the table, the area that fits both is "the narrower width and the shorter height". Add the amount that shifts depending on how the page is printed to set the margins.

The 3mm on the left and right covers printing Letter data on A4. If you only print from A4 to Letter, you do not need to add it.

For a margin of 15mm, the calculation is as follows.

• Top: 15 + 8.8 = 23.8 → 24mm
• Bottom: 15 + 17.6 = 32.6 → 33mm
• Left and right: 15 + 3 = 18mm

For documents that may be printed on either paper, a wider bottom margin keeps anything from being cut off.

Printers have an edge where they cannot print. Its width depends on the model, so also check the "printable area" in the manual.

What about images made in pixels?

For a 300dpi image, the area that fits both sheets is 2480 × 3300 pixels. That is the narrower width and the shorter height in the px (300dpi) column.

How to think about pixel counts is explained in A4 size in pixels. Keep important text and faces well inside this area.

What are common mistakes with the difference between Letter and A4?

The most common one is printing a Letter PDF on A4 with "Fit". The dimensions of the form change.

Other mistakes are in the table below.

When a document arrives, check two things in the preview before printing: the bottom edge and the scale.

What terms appear when reading about Letter size and A4?

The terms you will meet when reading about the difference between Letter size and A4 are in the table below.

Of these terms, "A size" is the one that most often trips people up with Japanese documents.

What else should you know along with the difference between Letter and A4?

Also learn how Letter compares with other papers, its aspect ratio and envelopes. Then documents from overseas will no longer confuse you.

How does B5 differ from Letter size?

B5 is much smaller than Letter, shorter in both width and height.

Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1

Printing a Letter document on B5 shrinks it to roughly 80%. The calculation is below; use the smaller value, about 84%.

• Width: 182 ÷ 215.9 ≈ 84%
• Height: 257 ÷ 279.4 ≈ 92%

What is the aspect ratio of Letter size?

The aspect ratio of Letter is about 1 : 1.29. That is closer to a square than A4's 1 : 1.414.

Because the ratios differ, you cannot fit a photo or figure exactly on both. Design it on the assumption that one of them will have a margin.

How do you put Letter documents in a Japanese envelope?

Letter documents fit in envelopes made for A4. But because Letter is 5.9mm wider, avoid envelopes that are a tight fit.

You can check Japanese envelope sizes in the envelope table of the paper size list. For a document folded in three, use a Nagagata No. 3 envelope as a guide, just as for A4.

Frequently asked questions about Letter size and A4

How big is Letter size?

It is 8.5 × 11 inches. In mm, it is 215.9 × 279.4mm, as the table shows.

It is a North American paper defined by round numbers in inches.

Which is bigger, Letter size or A4?

A4 has about 3.4% more area. However, Letter is 5.9mm wider.

Rather than asking which is bigger, look at which of the width and height does not fit.

How do you print a Letter document on A4?

In the print dialog, choose "Fit to paper", or set the output paper size to A4 in the driver. The page shrinks to about 97% and fits in full.

For a form with fixed dimensions, print at actual size and check the 3mm cut on the left and right.

How do you print an A4 document on Letter?

Choose "Fit to paper" or "Shrink oversized pages", and the page shrinks to about 94% and fits.

If you print at actual size, the bottom, or the top and bottom, will be cut off. The safe way is to remake the document for the paper used in the recipient's country before sending it.

Can you print on Letter size at a convenience store?

At many convenience stores, Letter is not among the printable papers. The document will be printed fitted to A4 or a similar size.

Print documents that need exact dimensions on a home or office printer that can take Letter paper.

How do you change Letter size to A4 in Word?

In "Page Setup", on the "Paper" tab, change the paper size to A4.

After the change, the line flow shifts, so review every page.

Sources

• ISO 216:2007 Writing paper and certain classes of printed matter. Trimmed sizes. A and B series (ISO)
• JIS P 0138 Paper finishing dimensions (Japanese Industrial Standards Committee, JIS search)
• Y14.1 Drawing Sheet Size and Format (ASME)
• CSS Values and Units Module Level 3: Absolute lengths (W3C)
• Page Setup - Paper options (Microsoft Support)
• Scale a worksheet (Microsoft Support)
• Troubleshooting PDF Print Size (Adobe)
• Change Page Output Options Before Printing on Mac (Apple Support)
• Print by Scaling (Canon Manual)
• [[Page Setup] Sheet Screen Description (Canon imagePROGRAF Manual)](https://ij.manual.canon/ij/webmanual/PrinterDriver/W/TC-21/CO/JP/PPG/Dg-pagesetup.html)
• Paper size mismatch errors (Epson FAQ)