PDFs from different sources rarely agree on page size. A scanner set to Legal, a report authored on A4 and a form exported as US Letter can all end up in the same folder, and combining or printing them together produces awkward results: pages that print with the wrong margins, a scanner that crops content because a print driver assumed the wrong size, or a merged document where every other page looks a slightly different size on screen.
Nothing is uploaded to make this happen. The PDF is parsed, its pages rescaled and the file rewritten entirely on your own device using a PDF library that runs in the browser tab, so a contract or a scanned form never has to leave your machine to get a consistent page size.
When you need to resize PDF pages
The clearest sign is a document, or a set of documents about to be merged, where the pages are not all the same size. Printing a mixed batch on a single printer setting, filing a scanned form alongside a digitally authored report, or preparing a document for a submission portal that specifies a required page size are all situations where mismatched pages cause real problems rather than just looking slightly odd.
It also comes up when a document was authored for the wrong region. A4 is the norm almost everywhere outside North America, while US Letter and Legal dominate within it, and a document created for the wrong audience often needs its page size changed before it prints predictably on a local printer. Converting a US Letter pdf to a4 before sending it to a European or Asian office is one of the most common single cases this tool handles.
- Use a pdf page resizer before merging documents that were scanned or exported at different page sizes.
- Change pdf page size to A4 or Letter to match a destination country's printing convention.
- Resize pdf pages before submitting to a portal or agency that requires a specific size.
- Standardise a batch of scanned forms that a scanner produced at inconsistent sizes.
- Fix a document that was accidentally authored at Legal size when Letter was required.
Choosing fit or stretch
Fit scales the page content uniformly, keeping its original proportions, and centres it inside the new page size with even margins on the sides that do not match exactly. This is the safer default: text stays legible, images keep their aspect ratio and nothing looks stretched or squashed.
Stretch scales width and height independently so the content fills the new page size exactly, with no added margin. This is the right choice when the source content was designed to fill its original page edge to edge and a small margin change matters less than keeping the layout at full size, but it will distort a page whose original aspect ratio does not match the target size, so a square diagram from a Legal page stretched to fit A4 will look visibly wider or taller than it did originally.
What resizing changes and what it does not
The PDF page size, formally the MediaBox, is rewritten to the target dimensions, and a scaling transform is applied to the page content so it lines up with the new box, whether that is a fitted or a stretched scale. Text stays selectable, images keep their original pixel data and vector graphics remain vectors, since none of the underlying content is rasterised or re-encoded during the resize.
What does change, deliberately, is apparent size on the printed page. A stretch resize changes the proportions of anything on the page, and a fit resize changes the effective margin around content whose aspect ratio does not match the target size exactly. Neither operation improves or degrades the resolution of embedded images, since it works by transforming coordinates rather than re-rendering pixels.
Choosing a target page size
A4 measures 210 by 297 millimetres and is the standard almost everywhere outside North America. US Letter, at 8.5 by 11 inches, is the standard within the United States and Canada. US Legal, at 8.5 by 14 inches, is longer than Letter and is used mainly for contracts and certain legal filings. Pick the size that matches the printer, portal or regional convention the finished document needs to satisfy.
A MediaBox rewrite, page by page: how the pdf page resizer works
For every page, the tool reads the current MediaBox dimensions, computes the scale factor needed to reach the target size under your chosen mode, then rewrites the MediaBox, CropBox and other page boxes to the new size while applying a matching transform to the page's content stream and its annotations. That keeps everything on the page, including form fields and links, aligned with the new dimensions.
All of this happens through a PDF document library running entirely inside your browser tab, so there is no upload wait and no size limit beyond what your device's memory can hold. Rewriting a handful of coordinate values per page is far lighter than re rendering content, which is why resizing a hundred page mixed batch finishes in a fraction of a second.
| Size | Dimensions | Common region |
|---|---|---|
| A4 | 210 x 297 mm | Most of the world outside North America |
| US Letter | 8.5 x 11 in | United States and Canada |
| US Legal | 8.5 x 14 in | Contracts and legal filings in North America |
How to resize PDF pages
- 1
Open your PDF
Drag a PDF onto the drop area or click to browse. The page count and current sizes are read immediately.
- 2
Choose a target size
Pick A4, US Letter or US Legal as the size every page should become.
- 3
Choose fit or stretch
Fit keeps proportions and centres content. Stretch fills the new page exactly, which can distort content.
- 4
Resize and download
Press resize and download the new PDF. Every page now shares the same dimensions.
Related tools worth bookmarking
Sources and further reading
- ISO 32000-2: Document management, PDF 2.0The current international standard defining the MediaBox and page geometry this tool rewrites.iso.org
- W3C: CSS Paged Media ModuleThe specification describing standard page size conventions such as A4 and Letter.w3.org
- MDN: File APIThe browser API this tool uses to read a dropped PDF locally without an upload.developer.mozilla.org
Frequently asked questions
Common questions about the pdf page resizer.
No. The tool reads each page's current MediaBox out of the document already parsed in memory, computes the scale factor for the target size and rewrites the MediaBox, CropBox and content transform in place. A scanned form sized to the wrong region never needs to travel anywhere to have its dimensions corrected, since the whole rescale is a set of coordinate rewrites on data your tab already holds.
No. The tool works by rewriting page boxes and applying a scaling transform to existing content, rather than rendering pages to pixels and re-encoding them. Text stays selectable and images keep their original resolution, though a stretch resize does change the proportions of what is on the page.
Fit scales content uniformly and centres it inside the new page, preserving proportions with even margins where the aspect ratio does not match exactly. Stretch fills the new page exactly by scaling width and height independently, which can visibly distort content whose original aspect ratio differs from the target size.
This tool applies the chosen target size to every page in the document in one pass, since a document usually needs a single consistent page size throughout. Split out the pages that need a different treatment first if only part of a document requires resizing.
Annotations, including form fields and link boxes, are scaled along with the page content so they remain aligned with what they used to point to or sit over. A field that used to sit under a signature line stays under that line after the page is resized.
Printer scale settings only change how a page looks on that one print job. A pdf page size converter rewrites the file itself, so the new size is consistent everywhere the document is opened, previewed, merged with other files or archived, not only inside one print dialog.