A4 vs Letter paper size: PDF page sizes in mm, inches and points
A4 is 210 × 297 mm, or 595 × 842 PDF points. Letter is 8.5 × 11 inches, or 612 × 792 points. Use Letter in the United States and Canada. Use A4 in most other countries. One PDF point is 1/72 of an inch.
What is the size of each PDF page format?
This table gives the portrait size of each format, width × height. A PDF file stores the page size in points. One point is 1/72 of an inch, so 72 points are 1 inch or 25.4 mm. The point values are rounded to the nearest whole point.
| Format | Millimeters | Inches | PDF points | Common use |
|---|---|---|---|---|
| A3 | 297 × 420 | 11.69 × 16.54 | 842 × 1191 | Posters, drawings, large tables |
| A4 | 210 × 297 | 8.27 × 11.69 | 595 × 842 | Letters and documents in most countries |
| A5 | 148 × 210 | 5.83 × 8.27 | 420 × 595 | Notebooks, flyers, small booklets |
| B4 | 250 × 353 | 9.84 × 13.90 | 709 × 1001 | Large forms, some newspapers |
| B5 | 176 × 250 | 6.93 × 9.84 | 499 × 709 | Books, school notebooks |
| Letter | 215.9 × 279.4 | 8.5 × 11 | 612 × 792 | Letters and documents in the US and Canada |
| Legal | 215.9 × 355.6 | 8.5 × 14 | 612 × 1008 | Contracts and legal forms in the US |
| Executive | 184.2 × 266.7 | 7.25 × 10.5 | 522 × 756 | Office notes and letters in the US |
| Business card | 50.8 × 88.9 | 2 × 3.5 | 144 × 252 | US business cards, usually landscape |
The A and B sizes come from the ISO 216 standard. Each A size is half of the size before it: two A4 pages make one A3 page. Letter and Legal are North American sizes, and they have the same width of 8.5 inches.
To calculate points from millimeters, divide by 25.4, then multiply by 72. For example, A4 is 210 mm wide: 210 ÷ 25.4 × 72 = 595.28 points.
Which page size should you use for a PDF?
Use the paper size of the country where the reader prints the PDF. Most offices use only one size of paper.
- Letter: the United States and Canada. Also some countries in Latin America, for example Mexico.
- A4: most other countries, for example the countries of Europe, the United Kingdom, India, Japan and Australia.
- Legal: contracts and some legal forms in the United States.
- A3: a large table, a plan or a poster.
- A5: a small booklet, or two A5 pages printed on one A4 sheet.
PDFriend has all the sizes in the table above. Text to PDF and Web to PDF always make A4 pages. For a web page on Letter paper, print it from Chrome and set the paper size there, as in how to save a website as a PDF on Android.
Tip: if you do not know the country of the reader, choose A4. A4 is the most common paper size in the world. A printer with Letter paper scales an A4 page with only a small change.
How many pixels does a sharp PDF page need?
The page size is in inches or millimeters, but a photo is in pixels. The sharpness of a printed page depends on the pixels for each inch (ppi). A common rule: 300 ppi for photos, and 150 ppi for text documents.
In PDFriend, the Image quality option sets the most pixels on the long side of each image. This table gives the result for one image that fills a full page with no margin. A smaller source photo gives fewer pixels.
| Image quality | Long side, at most | On A4 (11.69 in) | On Letter (11 in) | Use it for |
|---|---|---|---|---|
| Low | 1200 px | about 103 ppi | about 109 ppi | A small file to read on a screen |
| Medium | 2000 px | about 171 ppi | about 182 ppi | Email and text documents |
| High | 3000 px | about 257 ppi | about 273 ppi | |
| Original | 4096 px | about 350 ppi | about 372 ppi | Photos and the best print |
A screenshot, a chart or a black and white scan stays lossless at every quality, because it has few colors. With High or Original, an unchanged JPG photo goes into the PDF with its original data. To make a finished PDF smaller, read how to compress a PDF on Android.
When should you use Fit to image?
Fit to image is not a paper size. It makes each page the same shape as its image, so no white border shows. Use it to keep photos exactly as they are, or to show the PDF on a screen only.
Do not use Fit to image for a PDF that people print. The pages can have different sizes, and a printer adds its own white border. For print, choose A4 or Letter.
How do orientation and margins work?
The orientation sets which side of the page is long. PDFriend has 3 options:
- Auto: a wide image gets a landscape page. A tall image gets a portrait page.
- Portrait: every page is taller than it is wide.
- Landscape: every page is wider than it is tall. A landscape A4 page is 842 × 595 points.
The margin is the white space between the edge of the page and the image. PDFriend has 4 margins:
| Margin | Points | Inches | Millimeters |
|---|---|---|---|
| None | 0 | 0 | 0 |
| Small | 18 | 0.25 | 6.35 |
| Medium | 36 | 0.5 | 12.7 |
| Large | 72 | 1 | 25.4 |
For a PDF that people print, use a Small or a larger margin. Many printers cannot print to the edge of the paper, so an image with no margin can lose a thin strip at each edge.
How do you choose the page size in PDFriend?
You choose the page size in the PDF options sheet, just before the app makes the PDF. The same sheet has the orientation, the margin and the image quality.
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Open the PDF options
In the PDFriend editor, tap Convert to PDF. The PDF options sheet opens.
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Choose the page size
Under Page size, select A4, Letter or another size. Select Fit to image to make each page the same shape as its image.
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Choose the orientation and the margin
Under Orientation, keep Auto or select Portrait or Landscape. Under Margin, select None, Small, Medium or Large.
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Create the PDF
Tap Create PDF. Every page of the PDF has the size that you selected.
Which page sizes does the iPhone app have?
PDFriend is also an iPhone app (iOS 26 and later). The PDF options on iPhone have the same page sizes as on Android: Fit to image, A3, A4, A5, B4, B5, Letter, Legal, Executive and Business card.
Questions and answers
What is the difference between A4 and Letter?
A4 is 210 × 297 mm (8.27 × 11.69 in). Letter is 215.9 × 279.4 mm (8.5 × 11 in). A4 is about 6 mm narrower and about 18 mm taller than Letter.
What is the size of an A4 page in PDF points?
An A4 page is 595 × 842 points. One PDF point is 1/72 of an inch, so the exact values are 595.28 × 841.89 points.
Should I use A4 or Letter?
Use Letter in the United States and Canada. Use A4 in most other countries. If you do not know where the reader lives, A4 is the most common size in the world.
What happens if I print an A4 PDF on Letter paper?
Most printers scale the page to fit the paper. The page becomes a little smaller, and a white border shows at the top and the bottom. The text stays readable.
Is B5 the same size in Japan?
Not always. This guide gives the ISO 216 B sizes: B4 is 250 × 353 mm and B5 is 176 × 250 mm. The Japanese JIS B sizes are a little larger.
Which image quality do I need to print an A4 PDF?
Choose High. It keeps up to 3000 pixels on the long side of each image, which gives about 257 pixels per inch on a full A4 page. Medium gives about 171 pixels per inch, which is enough for text documents.
Which page sizes does PDFriend have?
Fit to image, A3, A4, A5, B4, B5, Letter, Legal, Executive and Business card. Text to PDF and Web to PDF always make A4 pages.
What does Fit to image do?
Fit to image makes each page the same shape as its image. There is no white border around the photo. The pages of the PDF can have different sizes.