Guide
How to Merge PDFs With Different Page Sizes
Combine PDFs with mismatched page sizes into one tidy document — standardize to A4 or Letter in your browser, free and private.
Merging PDFs is easy — until the pages don't match. Combine a scanned A4 contract, a Letter-size invoice, and a landscape spreadsheet, and you get one document that jumps between sizes and orientations every few pages. It prints badly, looks unprofessional, and is annoying to read. The fix is to standardize every page to a single size as you merge.
Why Mismatched Pages Happen
Every PDF page carries its own dimensions. A document scanned on an A4 scanner, a US invoice in Letter, and a slide exported in landscape all have genuinely different page boxes. A basic merge just stacks them as-is, preserving each original size. That's correct behaviour — but it's rarely what you want when the result is one document meant to read as a whole.
How to Merge and Standardize, Step by Step
- 1
Open the Merge PDF tool
Like everything here, it runs in your browser — your files aren't uploaded.
- 2
Add your PDFs and set the order
Drag the rows to arrange the files in the order you want them combined.
- 3
Choose Standardize and pick a target size
Select A4 or Letter and an orientation. Auto fits each page sensibly based on its own proportions.
- 4
Merge and download
Every page is now the same size, with the original content scaled to fit and centered.
Will Standardizing Distort My Content?
No. Each page is scaled to fit the target size while keeping its aspect ratio, then centered — so nothing is stretched or cropped. A page that is a different shape simply gets even margins around it. Text stays sharp and selectable because the content is kept as vectors, not flattened into an image.
When to Keep Original Sizes Instead
If your PDFs are already the same size, or you specifically need each page to keep its exact dimensions (some forms and legal documents do), choose "Keep original sizes" instead. Standardizing is for the common case: a pile of mismatched pages you want to read and print as one clean document.