A4 and Letter are the two PDF page sizes most people meet, and they are easy to confuse because they look similar on a screen. They are not the same. If you pick the wrong one, a printer may shrink the page, crop a footer, or leave an uneven white border.
Choose the size the recipient asked for. If nobody specified a size, match the paper that is loaded in the printer that will produce the file, or the convention of the country where the document will be printed.
The actual measurements
A4 is defined by the ISO 216 standard and measures 210 by 297 millimeters (about 8.27 by 11.69 inches). It is the everyday office paper size in most countries outside North America, and it is what many international universities and immigration forms expect.
Letter, often labeled US Letter, measures 8.5 by 11 inches (215.9 by 279.4 millimeters). It is the common size in the United States, Canada, and Mexico. Compared with A4, Letter is a little wider and a little shorter.
That small gap is enough to matter. A document written on Letter and printed on A4 paper can lose a sliver of the left or right margin, or the printer may scale the whole page down. A document written on A4 and printed on Letter can lose part of the top or bottom, which is where page numbers and footers often sit.
Picture a two-page letter with “Page 1 of 2” sitting 12 millimeters from the bottom of an A4 page. Printed on Letter paper without scaling, that footer can fall off the sheet. The file looked fine on screen because the viewer zoomed the page to fit the window.
Which size should you pick?
- Follow written instructions. If an application, journal, or school portal says “A4 PDF” or “Letter size,” that instruction wins.
- Job applications. Use the size common where the employer is. A US role typically expects Letter. An international role, unless it says otherwise, often expects A4.
- Schoolwork. Use whatever your course handbook lists. Mixing sizes inside one assignment (a Letter essay plus an A4 appendix) looks sloppy when printed as a set.
- Travel and official forms. Immigration and visa checklists frequently specify A4, even if you live in a Letter country, or the reverse. Read the checklist.
- When you truly do not know. Ask, or look at a template the organization provided. Guessing is how footers get cropped.
Set the size before you create the PDF
The cleanest approach is to set A4 or Letter in the original program, then export.
- Google Docs: File > Page setup, then choose A4 or Letter. After that, use File > Download > PDF Document. Details are in how to save a Google Doc as a PDF.
- Microsoft Word: Layout (or Page Layout) > Size, pick A4 or Letter, then export or print to PDF. You can also upload the Word file to Word to PDF once the size is correct in Word.
- Excel or Google Sheets: set the page size in Print settings, check the preview for columns that spill onto extra pages, then export. If columns still clip, see how to convert Excel to PDF without cutting off columns.
- A webpage: the browser print dialog includes a paper size menu. Choose A4 or Letter before you save, as described in how to save a webpage as a PDF.
Photos and scans: you choose the page size at conversion
Phone photos do not have an A4 or Letter size until you place them on a page. OurPDFPal's JPG to PDF tool lets you pick A4, Letter, or Fit to image.
Use A4 or Letter when the photos are meant to be printed or uploaded as formal pages (ID copies, handwritten homework, signed forms). Use Fit to image when you want each photo to keep its own shape, such as a wide receipt. You can also set margins (None, Small, or Medium) and orientation (Auto, Portrait, or Landscape).
For a stack of pages that should look like one document, pick one page size and one margin setting for the whole batch, then drag the thumbnails into order.
If a finished PDF is already the wrong size, creating it again from the source file is better than stretching the pages. Stretching can distort text. OurPDFPal does not offer a website tool that redesigns an existing PDF's page size, and you should not expect a simple convert step to reflow a Word-like layout inside a finished PDF.
Mixing A4 and Letter in one merged file
Merge PDF joins pages as they are. If you merge an A4 letter with a Letter resume, the combined PDF will contain both sizes. That is allowed, and many viewers handle it, but a printer may prompt for paper changes or scale pages inconsistently.
When the packet needs to look uniform, export each source file at the same size first, then merge. After merging, open the file and scroll it as a print preview. If one page looks shorter than the next, you are seeing the A4/Letter difference in action.
Print shops will often ask which stock to load before they print a stack of PDFs. If you hand them a mixed file, expect a pause while they decide whether to scale pages. Exporting the whole set at one size avoids that conversation.
Frequently asked questions
Is A4 the same as Letter?
No. A4 is 210 by 297 mm. Letter is 8.5 by 11 inches (215.9 by 279.4 mm). Letter is slightly wider and shorter than A4.
Which PDF page size should I use for an international application?
Use the size named in the instructions. If the form says A4, export A4 even if your computer defaults to Letter, and the other way around.
Why does my PDF look fine on screen but print with a cut-off footer?
The file is probably A4 and the printer is loaded with Letter paper, or the reverse. The viewer fitted the page to your screen. The printer did not. Export again at the paper size you will print.
Can I convert a Letter PDF to A4 without changing anything else?
Changing the canvas size is not the same as redesigning the document. The safer path is to set the correct size in Word, Google Docs, or your spreadsheet and export a new PDF.
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