Resize PDF online free: change page size to A4, Letter, and more

Change the page size of any PDF to A4, Letter, A3, Legal, or a custom size using the resize PDF tool at ToolHQ. No upload, no account: the entire conversion runs in your browser and your file never leaves your device.

Resizing a PDF means changing the dimensions of the page canvas. You might increase the page size to add more white space for printing and binding, reduce it to make a smaller, more portable document, or standardise a mixed-format PDF where some pages are different sizes. Content can be scaled to fit the new page size, or left at its original size with additional margin added around it.

This is different from compressing a PDF (which reduces file size) or rotating a PDF (which changes orientation). Resizing changes the actual physical dimensions of the page as a printing or display surface.

Key Takeaways

• Change PDF page size to any standard format: A4, Letter, A3, Legal, or custom dimensions
• Content can be scaled to fit the new page size or positioned within added white space
• Useful for print preparation, document standardisation, and layout correction
• Reference table of common ISO paper sizes included below
• Your file never leaves your device

---

What resizing a PDF means and how it works

Every PDF page has a defined width and height, specified in points (1 point = 1/72 inch). These dimensions are set when the PDF is created and stored in the PDF's page structure. When you resize a PDF, you are changing these stored dimensions.

The ISO 216 international paper size standard defines the A and B series paper sizes used in most countries. The ISO 32000 PDF standard supports any page dimensions, but for practical use, most documents target one of the standard sizes to ensure correct printing behaviour.

Two approaches to resizing exist:

Scale to fit: The content of each page is proportionally scaled up or down so it fills the new page size as much as possible, while maintaining the original aspect ratio. This is the right approach when you want to change the page size and have the content fill the new canvas.

Resize canvas only: The page dimensions are changed but the content is left at its original size and position. This adds white space around the content if the new size is larger, or crops content if the new size is smaller. This is useful when you want to add margin space around a tight layout.

ToolHQ's resize PDF tool processes your file entirely in your browser. Your file never leaves your device.

---

When you need to resize a PDF

Preparing for print: Your document was created at screen resolution for digital distribution and now needs to print on A4 or Letter paper. Resizing ensures the content fills the page correctly.

Standardising a document batch: You have received PDFs from multiple sources with mixed page sizes (some A4, some Letter, some custom). Resizing standardises them all to one size before merging or archiving.

Fixing a layout from a different region: Documents created in the US default to Letter size (8.5 x 11 inches), while those from Europe and most of the world use A4 (210 x 297mm). A4 is slightly taller and narrower than Letter. Resizing from one to the other ensures the document prints correctly on the intended paper.

Creating a larger version for annotation: Resize to A3 to print a document at twice the size, leaving room for handwritten notes or markup.

Mini-story: A content strategist received a presentation deck from a US colleague in Letter format, but needed to print it in the UK on A4 paper. When printed without resizing, the document printed with the wrong margins and cut off the footer. She used ToolHQ's resize PDF tool to convert all pages to A4 in under 30 seconds. The printed result was correctly formatted on the standard UK paper size.

Resize your PDF now at ToolHQ's PDF page resizer.

---

How to resize a PDF step by step

1. Open the tool. Visit ToolHQ's resize PDF tool.
2. Upload your PDF. Click to select or drag and drop your file. Processing is browser-local; your file stays on your device.
3. Select the target page size. Choose from the standard sizes in the dropdown (A4, Letter, A3, Legal, etc.) or enter custom dimensions.
4. Choose scale or canvas-only mode. Select whether to scale the content to fit the new page, or simply change the page canvas size.
5. Resize and download. Click "Resize". Download the output PDF and verify the page size is correct in your PDF viewer (File > Properties typically shows page dimensions).

---

Common paper size reference table

Use this table to identify the correct dimensions for standard paper sizes. The most commonly needed are A4 and Letter.

Size name	Width x Height (mm)	Width x Height (inches)	Common use
A3	297 x 420mm	11.7 x 16.5 in	Large format printing, posters
A4	210 x 297mm	8.3 x 11.7 in	Standard international document size
A5	148 x 210mm	5.8 x 8.3 in	Booklets, flyers
Letter	216 x 279mm	8.5 x 11.0 in	Standard US document size
Legal	216 x 356mm	8.5 x 14.0 in	US legal documents
Tabloid	279 x 432mm	11.0 x 17.0 in	US large format printing
B5	176 x 250mm	6.9 x 9.8 in	Books and notebooks

The A-series is defined by the ISO 216 standard: each size is exactly half of the next larger size. A4 is half of A3; A5 is half of A4. This mathematical relationship ensures consistent scaling.

Mini-story: A graphic designer was preparing a company brochure in A5 format for print. Her client then requested a version for their US partners in US Letter format. She used ToolHQ's resize PDF tool to scale the A5 brochure to Letter size with content scaling enabled. The result needed only minor manual text adjustments, saving several hours compared to rebuilding the layout from scratch in her design software.

---

Frequently asked questions

Will resizing a PDF change the text quality? If you scale the content to fit, text rendered as vector graphics (which is the case for most PDFs created from Word, InDesign, or similar software) will remain crisp at any size. Images embedded in the PDF may appear slightly softer if significantly upscaled.

Does resizing change the file size? Usually not significantly. The file size is primarily determined by the embedded images and fonts, not the page dimensions. A resize that only changes page dimensions without scaling content typically has minimal effect on file size.

Can I resize only specific pages in a PDF? Most resize tools apply the same page size to all pages. If you need different pages at different sizes, you would need to extract the pages, resize each group separately, and merge them back using ToolHQ's PDF merger.

What is the difference between A4 and Letter? A4 (210 x 297mm) is the international standard used in the UK, Europe, Australia, and most of the world. Letter (216 x 279mm) is slightly wider and shorter and is the standard in the US and Canada. A document in one format may have content cut off or awkward margins when printed on the other.

Can I resize a scanned PDF? Yes. A scanned PDF is essentially a collection of image pages. Resizing works the same way, scaling the image on each page to fit the new dimensions.

---

The short version

Resizing a PDF changes the page dimensions to a standard size like A4 or Letter, either by scaling the content to fit or by adjusting the canvas around the existing content. ToolHQ's resize PDF tool handles the conversion in your browser, supports all common ISO and US paper sizes, and processes your file without uploading it to any server. Use it to prepare documents for print, standardise a mixed-size batch, or adapt a US Letter document for international audiences who use A4.

Resize your PDF now at ToolHQ.

Related tools: PDF compressor | Organise PDF | Rotate PDF | Flatten PDF