How to Resize PDF Pages: Paper Sizes, Custom Dimensions, and Margins
PDF pages come in many sizes. A document created in the United States may use Letter (8.5 × 11 inches). A document created in Europe uses A4 (210 × 297 mm). A scanned receipt may be a non-standard size based on the scanner’s capture area. Resizing changes the page dimensions to match a standard or custom size.
This guide covers when resizing is appropriate, what the options mean, and when to use resize versus crop.
What Resizing a PDF Does
Resizing a PDF changes the physical dimensions of each page. When you resize from A4 to Letter (or vice versa), the tool:
- Creates a new page at the target dimensions
- Scales or places the existing content to fit
- Adds or removes space (margins) as needed
The exact behaviour — whether content is scaled to fill the new page or centered with added whitespace — depends on the tool and settings chosen.
Common Resize Scenarios
Converting between A4 and Letter
The most common resize task. A4 (210 × 297 mm, approximately 8.27 × 11.69 inches) is taller and narrower than Letter (8.5 × 11 inches). Converting between them adjusts the canvas size and may leave white space along one edge or require slight scaling.
This matters when:
- A European document needs to be printed on Letter paper in the United States (or vice versa)
- A PDF template designed for one size needs to be reformatted for another
- A document must match a submission requirement specifying a particular paper size
Adding margins to a margin-free document
Some PDFs — particularly those exported from design tools or scanned at full bleed — have content that extends to the page edges. This can cause printing issues on printers that have a non-printable border. Adding margins moves the content inward.
Reducing page dimensions
A document designed at a large format (A3, A2) needs to be converted to A4 for a standard print run. Scaling down preserves all content but makes text and images smaller.
Standardising mixed-size documents before merging
If you are about to merge several PDFs with different page sizes into one document, resizing them all to the same size first produces a consistent result.
Understanding the Settings
Target size
Standard paper sizes include:
- A4 (210 × 297 mm): International standard, dominant in Europe, Asia, and most of the world
- Letter (8.5 × 11 in, 215.9 × 279.4 mm): North American standard
- Legal (8.5 × 14 in): Used for some legal documents in North America
- A3 (297 × 420 mm): Larger international format, double the area of A4
- Custom: Specify exact width and height values
Orientation
Portrait places the shorter dimension as the width; landscape places the longer dimension as the width. If you are converting from portrait to landscape or vice versa, confirm that the content within the pages makes sense in the new orientation.
Margins
Margins add blank space around the content area. Adding margins to a content-to-edge document:
- Creates a print buffer (prevents content from being cut at the printer edge)
- Makes the document look more like a professional typeset layout
- Reduces the effective reading area
Margins can be set uniformly (same on all sides) or asymmetrically (different values for top, bottom, left, right).
Fit vs. fill
When the content’s aspect ratio does not match the target page’s aspect ratio, there are two approaches:
- Fit: Scale the content to be entirely visible within the target page, leaving white space where the aspect ratios differ
- Fill: Scale the content to fill the target page, potentially cropping edges where the aspect ratios differ
For document conversion, “fit” is almost always the safer choice — it guarantees nothing is cut off. “Fill” is appropriate when you specifically want the content to fill the entire page and are willing to accept some edge trimming.
Resize vs. Crop: Choosing the Right Tool
These two tools are often confused because both can change what is visible on a page:
| Resize PDF | Crop PDF | |
|---|---|---|
| What it changes | The page dimensions and content scale | The visible area of the page (trims edges) |
| Adds space? | Yes, when scaling down or adding margins | No |
| Removes content? | Potentially, when filling without fit mode | Yes, always removes edge content |
| Use for | Paper size conversion, margin addition, dimension standardisation | Removing scanner borders, trimming oversized margins |
Rule of thumb: If you need to change the paper size or add space, use Resize. If you need to remove unwanted edges, use Crop PDF.
Using PDFolio’s Resize PDF Tool
PDFolio’s Resize PDF tool runs locally in your browser:
- Add your PDF. Drop the file into the workspace.
- Choose the target size. Select a standard paper size or enter custom dimensions.
- Set orientation. Choose portrait or landscape.
- Configure margins. Set the margin values if you want to add space around the content.
- Choose fit or fill. Decide how content should be positioned within the new page size.
- Process. The resize runs locally.
- Download and verify. Open the result in a PDF viewer and confirm that the page dimensions, content position, and margin sizes are correct.
After Resizing
Resized PDFs are often ready to move into other workflows:
- Merge PDF: Combine with other documents that now match in size
- Page Numbers: Add numbering to the resized version
- Compress PDF: Reduce file size if margins or scaling increased it