Why Resize a PDF?
Different printers, countries, and submission portals expect specific page sizes. A document created on a US Letter-sized page will not print correctly on A4 paper without resizing, and vice versa. Common reasons to resize include:
- International printing: A4 is standard in most countries, while US Letter is used in North America
- Submission requirements: Government forms and academic journals may require specific dimensions
- Poster printing: Scaling a document up for large-format printing at conferences or events
- Consistency: Making sure all pages in a merged document share the same size
- Screen optimization: Adjusting page size for better on-screen reading
Understanding page sizes and how to convert between them is essential for anyone who works with PDFs across different regions or printing environments. This guide covers everything you need to know about resizing PDFs effectively.
Standard Page Sizes Reference
| Size | Dimensions (mm) | Dimensions (inches) | Common Use |
|------|-----------------|---------------------|------------|
| A4 | 210 x 297 | 8.27 x 11.69 | Standard in Europe, Asia, most of the world |
| US Letter | 215.9 x 279.4 | 8.5 x 11 | Standard in USA, Canada, Mexico |
| Legal | 215.9 x 355.6 | 8.5 x 14 | Legal documents in the USA |
| A3 | 297 x 420 | 11.69 x 16.54 | Posters, charts, architectural plans |
| A5 | 148 x 210 | 5.83 x 8.27 | Booklets, flyers, pocket guides |
| Tabloid | 279.4 x 431.8 | 11 x 17 | Newspapers, large spreadsheets |
The most common resizing task is converting between A4 and US Letter. While these sizes appear similar, the differences in height and width can cause content to be cut off or margins to appear uneven if not resized properly.
How to Resize a PDF Online
Step 1: Upload Your PDF
Open the [Resize PDF](/resize-pdf) tool and upload your document. The tool accepts PDFs of any size and page count. You can drag and drop your file or click to browse.
Step 2: Choose Target Size
Select the desired page size from the presets (A4, Letter, Legal, A3, A5) or enter custom dimensions in millimeters or inches. The tool shows a preview of how your content will fit on the new page size.
Step 3: Configure Scaling Options
Choose how your content should fit the new page:
- Fit to page: Scales content proportionally to fit within the new dimensions
- Fill page: Scales content to fill the entire new page, potentially cropping edges
- Stretch: Stretches content to match exact dimensions (may distort proportions)
For most use cases, "Fit to page" produces the best results.
Step 4: Download
Click resize and download the adjusted PDF. Content is scaled to fit the new page dimensions while maintaining readability.
Resize vs. Crop: Choosing the Right Tool
Understanding the difference between resizing and cropping is crucial for getting the results you want:
| Feature | Resize | Crop |
|---------|--------|------|
| Changes page dimensions | Yes | Yes |
| Scales content | Yes | No |
| Removes content | No (scales to fit) | Yes (trims edges) |
| Best for | Changing paper size | Removing margins |
| Content quality | May reduce if scaling up | Unchanged |
Resizing changes the entire page dimensions and scales content to fit. [Cropping](/crop-pdf) trims the visible area without scaling. If your content already fits but has extra white space, cropping is the better choice. If you need to change from one paper standard to another, resizing is the correct approach.
Tips for Best Results
Check orientation first: Make sure your document is in portrait or landscape to match the target size. Use [Rotate PDF](/rotate-pdf) to fix orientation before resizing.
Use Crop first: If you have unwanted margins, crop them before resizing for a cleaner result. See our [cropping guide](/blog/crop-pdf-pages-guide) for detailed instructions.
Flatten interactive elements: [Flatten the PDF](/flatten-pdf) before resizing forms to preserve field positions. Learn more in our [flattening guide](/blog/how-to-flatten-pdf).
Compress after resizing: Use [Compress PDF](/compress) if the resized file is larger than expected. Scaling up can increase file size.
Verify the result: Always review the resized PDF to confirm content looks correct before printing or sharing.
Maintain aspect ratio: When possible, resize between sizes with similar aspect ratios to minimize distortion. A4 and US Letter are close enough that content scales well between them.
Common Workflows
Converting US Letter to A4 for International Use
This is the most frequent resizing task for businesses working across borders:
Upload your Letter-sized PDF to Resize PDF
Select A4 as the target size
Choose "Fit to page" scaling
Download and verify the result
Compress the PDF if needed for email delivery — see our [email compression guide](/blog/how-to-compress-pdf-for-email)
Converting A4 to US Letter for American Clients
When sending documents to recipients in the United States: