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Have you ever downloaded a PDF only to find it’s an awkward, non-standard size that doesn’t fit your needs? Perhaps it's a poster-sized document you need to print on A4, or a legal document that must be converted to Letter size for a submission. Changing PDF page size can resolve issues like misaligned content, wasted paper, or poor readability.
In this guide, we’ll introduce how to resize PDF pages, including step-by-step methods for everyday users (no tech skills required) and a developer-friendly C# solution to automate bulk tasks.
- Standard Paper Sizes You Should Know
- Method 1: Using Free Online PDF Tools
- Method 2: Using Adobe Acrobat (Standard/Pro)
- Method 3: Using Windows Built-In Printer Feature
- Method 4: Using C# to Change PDF Page Size
- FAQ: Common PDF Resizing Questions
- Final Thoughts
Standard Paper Sizes You Should Know
When changing your PDF size, you'll likely use one of these common standards:
- A4 (210 x 297 mm / 8.27" x 11.69"): The international standard, used everywhere except North America.
- Letter (8.5" x 11" / 216 x 279 mm): The standard in the United States and Canada.
- Legal (8.5" x 14" / 216 x 356 mm): Often used for contracts and official documents.
- A3 (297 x 420 mm / 11.69" x 16.54"): Twice the size of A4, common for diagrams and small posters.
- Tabloid/Ledger (11" x 17" / 279 x 432 mm): Often used for newspapers or large presentations.
Method 1: Using Free Online PDF Tools
For quick, one-off jobs without installing software, free online tools are excellent. They work on any browser and support basic to moderate resizing needs.
Popular Tools: Smallpdf, PDF2Go, and Soda PDF.
General process to change PDF page size online:
- Go to the tool’s “Resize PDF” page (e.g., PDF2Go Resize PDF tool).
- Upload your PDF file by dragging and dropping or selecting it from your computer.
- Select a preset page size (A4, A3, Letter, etc.) from the dropdown menu, or enter custom dimensions.
- Click the "Start" button and then download the resized PDF.
Note: While convenient, online PDF resizing tools may pose privacy risks for sensitive documents, and free plans usually limit file size and number of tasks.
Also Read: How to Crop PDFs for Free (3 Easy Methods)
Method 2: Using Adobe Acrobat (Standard/Pro)
For precise control, especially with professional or complex documents, Adobe Acrobat (Pro or Standard) is the industry standard.
How to resize PDF pages with Adobe Acrobat:
- Open your PDF in Acrobat and go to “File > Print” (or press “Ctrl+P”).
- Choose "Microsoft Print to PDF" as your printer.
- Go to "Page Setup" and select your desired paper size (e.g., Letter, A4).
- In the “Page Size & Handling” section, choose “Fit” to scale the content to the new page size.
- Click "Print" to apply the changes.
Best for: Users who need high precision, batch processing, or are working with sensitive or professional documents.
Method 3: Using Windows Built-In Printer Feature
This is a clever workaround available to all Windows 10 and 11 users. It uses the printer settings to effectively create a new PDF with a different size.
Steps to resize PDF pages in Windows:
- Open your file in any PDF viewer (like the built-in Microsoft Edge).
- Press “Ctrl + P” or click the printer icon.
- Choose “Microsoft Print to PDF” as your printer, and click "More settings."
- Look for a "Paper Size" dropdown and select your desired size (e.g., A4, Letter).
- Check "Fit to printable area” to scale the content appropriately to the new size.
- Click “Print” to save the new, resized PDF under a different name or location.
When to Use This Method: You’re a Windows 10/11 user and want a free, no-installation solution to resize simple PDF documents.
Method 4: Using C# to Change PDF Page Size
For developers, automating PDF resizing (e.g., in apps, batch jobs, or workflows) saves time and reduces errors. Spire.PDF for .NET is a robust library that allows you to adjust the PDF page sizes via C#.
How to set PDF page size in C#:
The code below creates a new PDF with A3-sized pages, then scales and copies content from the original PDF to fit the new dimensions.
using Spire.Pdf;
using Spire.Pdf.Graphics;
using System.Drawing;
namespace ChangePDFSize
{
class Program
{
static void Main(string[] args)
{
// Create a PdfDocument instance
PdfDocument originPdf = new PdfDocument();
// Load the original PDF document
originPdf.LoadFromFile("Sample.pdf");
// Create a new PDF document
PdfDocument newPdf = new PdfDocument();
// Loop through the pages in the original PDF
foreach(PdfPageBase page in originPdf.Pages)
{
// Add an A3-sized page to the new PDF
PdfPageBase newPage = newPdf.Pages.Add(PdfPageSize.A3, new PdfMargins(0));
// Create a PdfTextLayout instance
PdfTextLayout layout = new PdfTextLayout();
// Set text layout as one page to ensure the content will scale to fit page size
layout.Layout = PdfLayoutType.OnePage;
// Create a template from the original page
PdfTemplate template = page.CreateTemplate();
// Draw the templates onto the pages in the new PDF
template.Draw(newPage, new PointF(0, 0), layout);
}
// Save the resized document
newPdf.SaveToFile("ChangePageSizeToA3.pdf");
}
}
}
Core Methods:
- PdfDocument.Pages.Add(PdfPageSize size, PdfMargins margins): Adds a new page to a PdfDocument with a specified size and margins.
- PdfPageBase.CreateTemplate(): Captures content (text, images, shapes, etc.) from the original page.
- PdfTemplate.Draw(PdfPageBase targetPage, PointF location, PdfTextLayout layout): Draws the content of a PdfTemplate onto the new PDF page, with positioning and layout rules.
Here’s the result PDF file with a page size of A3 (11.69 x 16.54 inch):
If you need to customize the PDF page size, refer to: Change PDF Page Size to a Custom Paper Size in C#
FAQ: Common PDF Resizing Questions
Q1: Will resizing a PDF page distort my text or images?
A: When done correctly, the content should scale proportionally. However, drastic size changes (e.g., A4 to A6) can make text very small or images pixelated. Always check the output file. Using the "Fit to page" or similar scaling option is crucial to maintain proportions.
Q2: Is there a free Mac alternative to Microsoft Print to PDF?
A: Yes, use Mac’s default Preview app:
- Open the PDF in Preview.
- Go to “File > Print”.
- Click the “Paper Size” dropdown and select your desired paper size from the list.
- Click “PDF” (bottom-left) and choose "Save as PDF" to export.
Q3: Which method is best for batch resizing PDF pages?
A: Free online tools often have limitations on batch processing. Adobe Acrobat Pro has built-in batch actions for this purpose. For large-scale, automated batch processing, the programmatic C# method using Spire.PDF is the most efficient and powerful solution.
Q4: As a developer, is Spire.PDF free to use?
A: Spire.PDF for .NET offers a free community edition with limitations, which is good for evaluation and small projects. If you want to test the full functionality, you can apply for a 30-day trial license here.
Final Thoughts
Adjusting PDF page size is straightforward with online tools or Adobe Acrobat for general users. If you’re on Windows and want a reliable, offline option for simple documents, the built-in “Microsoft Print to PDF” feature is perfect. For automation or app integration, Spire.PDF for .NET offers a powerful C# solution. No matter which tool you choose, always check the final PDF to ensure content and formatting stay correct. With this guide, you are now equipped to handle any PDF page size challenge efficiently.