Resize PDF Online — change page dimensions without distorting the content
Pick a standard preset or type a custom size, choose how content scales into it, add margins, and apply it to all pages, a range, or pages you select yourself.
The resize console
Upload a PDF, choose the new size and scaling rule, then apply it.
Drop your PDF here
or browse files
Pages
Preview of every page in your document.
2. New page size
4. Margins
Resizing is two decisions, not one
What new size the page becomes, and what happens to the content that was already on it — those are genuinely separate settings, and mixing them up is where most bad results come from.
A new canvas, then a placement rule
A Letter-size report that needs to go out as A4 for European colleagues, an architectural drawing that needs shrinking from A1 to A3 for a portfolio, an e-book that needs reformatting to fit a smaller tablet screen — each of these needs a specific new page size, but they don't all want their content handled the same way once that size changes.
pdf-lib creates a new blank page at your chosen dimensions, then places the original page's content into it according to the scaling mode you pick — stretched to fit it exactly, scaled down to fit inside it, scaled up to fill and crop it, or left at its original size and centered. Margins carve out a border the content won't be placed into.
Every control and what it changes
Presets or custom size
Five standard paper sizes plus a square preset, or type exact dimensions in mm, cm, inches, or points.
Lock aspect ratio
Changing width recalculates height automatically, so custom sizes don't come out stretched by accident.
Four scaling modes
Fit, Stretch, Keep Original Size, and Crop — each places existing content into the new page differently.
Margins
Reserve space on any side that content won't be scaled or centered into.
Three page-selection modes
All pages, a typed range, or click individual thumbnails to build your own list.
Scaling mode decides more than the dimensions do
The size you pick is only half the outcome — the scaling rule decides what happens to the content inside it.
Upload your PDF
Drag it onto the upload area, or click Select PDF. A thumbnail of every page appears right away.
Define the new page size
Use the control panel to set your new dimensions:
Apply and download
Click Resize PDF. Rename the output file if you like, then download the finished document.
Check the result
Open the downloaded file to confirm the size and scaling look right before sharing it further.
From one page size to another, cleanly
A Letter document resized to A4 with Fit to Page scaling.
An 8.5 × 11 inch page, needing to become A4 for international distribution.
With Fit to Page, the content is scaled proportionally into the new dimensions without stretching or cropping.
Situations where the page size itself is the problem
Cases where the document's dimensions, not its content, are what need to change.
| Use case | What resizing solves | Typical user |
|---|---|---|
| International distribution | Convert US Letter documents to A4 for colleagues or clients outside North America. | Business teams |
| Booklet preparation | Resize pages down to A5 or similar for printed booklets and pamphlets. | Publishers & print shops |
| Technical drawings | Scale a large-format architectural or engineering plan down to a portfolio-friendly size. | Architects & engineers |
| Submission requirements | Match a journal, university, or client's specified page dimensions before submission. | Students & researchers |
| Screen-sized PDFs | Resize fixed-layout PDFs to dimensions that better match a tablet or other screen-based reading workflow. | Readers |
| Print margins & page dimensions | Adjust page dimensions or add margin space when preparing a PDF for a print workflow. | Designers |
| Portrait or landscape page sizes | Change a PDF page to portrait or landscape dimensions while choosing how the existing content is fitted into the new page. | Office administrators |
| Sheet music & scores | Resize pages to fit a smaller music stand or tablet display. | Musicians |
Four scaling modes, four different outcomes
Same new page size, four very different results depending on how existing content is placed into it.
Fit to page (default)
Scales the content down or up so the whole page fits inside the new dimensions, preserving its proportions. May leave empty space on two sides if the aspect ratios don't match. A good default when you want to preserve the full page without stretching or cropping.
Stretch to fit
Stretches width and height independently to fill the new page exactly, with no empty space. If the aspect ratio changes, content will look visibly stretched or squashed — only use this when the target size shares the same proportions.
Keep original size (centered)
Content stays at its original dimensions and is centered on the new page. If the new page is smaller than the content, parts of it will be cut off at the edges — right for adding a border around content that must stay exactly as-is.
Crop to fit
Scales content up until it fully covers the new page, cropping whatever overflows the edges. No empty space, but parts of the original content are permanently trimmed away — best when filling the frame matters more than preserving every element.
When the resized file doesn't come out right
What's actually happening, and the fastest way through it.
Content looks stretched or squashed
Stretch to Fit was used with a target size that has different proportions than the original.
Switch to Fit to Page, which preserves proportions, or enable Lock Aspect Ratio when entering a custom size.
Part of the content is missing
Crop to Fit was used, and content near the edges was trimmed to fill the new page fully.
Switch to Fit to Page instead — nothing is cropped, though empty space may appear on two sides.
Clicking the Square preset shows an odd point value
The Square preset fills the custom-size fields directly in points, so 1000 × 1000 is what should appear.
Confirm the unit dropdown shows "pt" — if you'd rather work in mm or inches, switch units and the value converts automatically.
Clicking pages doesn't do anything
Page thumbnails only register selections when Apply to Pages is set to "Manually select pages."
Choose "Manually select pages" first, then click thumbnails to add or remove them from the list.
A password-protected PDF won't load
Encrypted files can't be read by the in-browser rendering engine.
Remove the password with a PDF unlock tool first, then upload the unlocked copy.
Resize button does nothing
No PDF has been uploaded yet.
Upload a PDF first — the Resize button becomes active once pages have loaded.
Content looks stretched
Why: Stretch to Fit with mismatched proportions.
Fix: Use Fit to Page or lock the aspect ratio.
Content is missing
Why: Crop to Fit trimmed the edges.
Fix: Use Fit to Page instead.
Odd Square preset value
Why: Confirm unit is pt.
Fix: Switch units to convert automatically.
Page clicks do nothing
Why: Not in Manual mode.
Fix: Select "Manually select pages" first.
Password-protected PDF won't load
Why: Encrypted files can't decode in-browser.
Fix: Unlock it first, then upload.
Resize button does nothing
Why: No PDF uploaded.
Fix: Upload a PDF first.
Getting the right size on the first try
A working order that avoids the most common redo.
Lock the aspect ratio for custom sizes
Unless you specifically want to stretch content, check Lock Aspect Ratio so width and height stay proportional.
Start with Fit to Page
It's the default for a reason — it scales content proportionally without cropping or stretching anything.
Use Manually Select for scattered pages
When the pages you need aren't a clean range, switch to Manually Select and click through the thumbnails.
Check the unit before typing dimensions
A width of "1000" means something very different in points versus mm — confirm the dropdown before entering numbers.
Keep the original file
Resizing creates a new document — keep the source PDF so you can try a different size or mode later.
Preview the result before sharing
Open the downloaded file and check a few pages before sending it on — resizing is fast to redo if something's off.
PDF resize FAQs
If something's not covered here, the troubleshooting section above likely has it.
Is it safe to upload my documents to resize them?
Yes. The entire resizing process happens locally in your browser — your files are never uploaded to a server.
Will resizing reduce the quality of my PDF?
The original content isn't re-compressed — the existing page is scaled to fit the new dimensions. Vector content stays sharp at any scale; raster images keep their original pixel data, so scaling them up can make them look softer, the same way enlarging any image would.
Can I apply different sizes to different pages?
One resize setting applies to a selection of pages at a time. To use different sizes for different pages, run the tool more than once — resize pages 1-10 to A4, download, then re-upload and resize pages 11-20 to A5.
What's the difference between the page selection modes?
All Pages applies the new size everywhere. Page Range applies it to the numbers or ranges you type in, like 1-3, 7. Manually Select Pages lets you click individual page thumbnails to build a custom list, useful when the pages you want aren't a clean range.
Can I undo a resize after downloading the file?
No — the downloaded file is a new, separate PDF. To undo, re-upload your original, unresized file and start over. Keep a copy of the original if you might want to try a different size later.
What happens to my file after I'm done?
Nothing — it was never uploaded. The resized PDF is generated in your browser and downloaded as a new file; the original stays untouched.
How this PDF resizer was built
See how the browser-based PDF resizer handles page dimensions, scaling modes, unit conversion, and page selection without sending the document to a server.
How to Build a Browser-Based PDF Resizer Using JavaScript
Covers page-dimension math, unit conversion, standard paper formats, and client-side PDF manipulation with pdf-lib.