When PDF Pages Are Different Sizes
Why it happens after merging, and how to make every page match.
The Short Answer
Merging a PDF copies every page exactly as it was, paper size included. If you combined an A4 letter, a US Letter form and a photo of a receipt, the merged file keeps all three sizes. Nothing went wrong in the merge.
To fix it, place every page on a sheet of one size, scaled to fit and centred. That keeps the text sharp and nothing gets cut off.
Make all pages the same size →How to Make Every Page the Same Size
- Open the PDF Page Size Changer and choose your PDF.
- Read the size table. It lists every page size in the file, in millimetres and inches, with the paper name where it matches one.
- Pick the target: US Letter, A4, US Legal, or the size of the first or largest page.
- Leave orientation on Keep each page's orientation unless you need every page portrait.
- Choose Scale to fit, or Shrink only if small pages such as receipts should stay at their real size.
- Click Resize Pages, then Download PDF.
Here is what the size table showed for a three-page test file we made from an A4 page, a landscape Letter page and a 4 × 6 inch page:
| Page | Size (mm) | Size (in) | Paper |
|---|---|---|---|
| 1 | 210 × 297 | 8.27 × 11.69 | A4 portrait |
| 2 | 279.4 × 215.9 | 11 × 8.5 | Letter landscape |
| 3 | 152.4 × 101.6 | 6 × 4 | 4 × 6 in landscape |
After converting to US Letter, all three pages were 8.5 × 11 inches, with the landscape pages still shown landscape.
Where the Different Sizes Come From
- A4 and US Letter. Most of the world uses A4 (210 × 297 mm). The US and Canada mostly use Letter (8.5 × 11 in). Documents from both end up side by side.
- Scans and phone photos. A page photographed or scanned with an app may be saved at whatever size the app chose, which is often not a standard paper size.
- Landscape pages. Slides, spreadsheets and wide tables are often landscape. A landscape Letter page is the same paper turned sideways, which most viewers show as a wider page.
- Receipts, tickets and cards. Small documents saved as PDFs keep their small size.
Things That Trip People Up
- A4 and Letter aren't the same shape. An A4 page on Letter is scaled to about 94% with white bands at the sides. A Letter page on A4 is scaled to about 97% with bands at the top and bottom. That's expected: the alternative is stretching or cropping.
- Small pages get enlarged. With Scale to fit, a receipt is blown up to fill the sheet. Choose Shrink only to keep it at real size.
- Sideways pages. A page that already looks rotated in your viewer stays that way. Fix it first with the PDF Page Rotator if it should be upright.
- Links and form fields. On resized pages these are not carried over. If a form's values must stay visible, flatten it first with the PDF Form Flattener.
- Locked files. A PDF with a password or restrictions has to be unlocked first with the PDF Password Remover.
If You Only Need a Printout
For a one-off print you may not need to change the file. In Acrobat or Acrobat Reader, open the Print dialog and, under Page Sizing, choose Fit to scale each page to the paper, or Shrink oversized pages to shrink only pages that are too big (Adobe's page sizing help). Other apps have similar options with different names.
That only changes the printout. A file you send, or upload to a portal that checks page size, still has mixed sizes until you fix the file itself.
Frequently Asked Questions
Why are my PDF pages different sizes after merging?
Merging copies each page exactly as it was, including its paper size. If one file was A4, another US Letter and a third a phone scan of a receipt, the merged PDF contains all three sizes. The merge didn't change anything; the sizes were already different in the original files.
How do I make all pages of a PDF the same size?
Use a tool that places every page onto a sheet of one size, scaled to fit and centred. The PDF Page Size Changer here does that in your browser: pick Letter, A4, Legal or the size of the first page, and download the result.
Will resizing the pages make the text blurry?
Not with a tool that keeps the pages as vector content. The page is scaled like a drawing, not turned into a picture, so text stays sharp and searchable. Tools that convert pages to images, or print to a PDF printer that rasterizes, can soften text.
Why is there a white border after resizing A4 to Letter?
A4 and US Letter have different shapes. A4 is narrower and taller, so an A4 page fitted onto Letter is scaled to about 94% of its size, leaving white bands at the left and right. Nothing is stretched or cut off to fill the gap.
Can I just fix it when I print?
Often, yes. Acrobat and Acrobat Reader have a Fit option under Page Sizing in the Print dialog that scales each page to the paper. That only affects that printout, though. If you are sending the file to someone else, or uploading it to a portal that checks page size, fix the file itself.
Do I lose anything when pages are resized?
Text, images and drawings are kept. On resized pages, clickable links, comments and fillable form fields are not carried over by this tool. Pages that are already exactly the target size are copied unchanged.