C# - How to Extract Pages from PDF

When working with PDF documents, splitting pages is a common requirement—for example, extracting specific chapters from a multi-page report, distributing meeting minutes by participant, or saving each page of a scanned document as a separate file. This article details how to split PDF pages in C# using a free library, with code examples for various scenarios.

Installation: Install the FreeSpire.PDF package via NuGet (Install-Package FreeSpire.PDF). This is a free community edition with no restrictions when processing up to 10 pages per operation. Exceeding 10 pages will result in truncation, so this library is suitable for lightweight tasks.

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1. Core Approach

Splitting a PDF essentially means: load source document → select target pages → create a new document → import pages → save. Free Spire.PDF provides a complete PdfDocument model that supports page-level copying and independent output.

Basic workflow:

1. Load the source PDF file.
2. Determine which pages to split (a single page, a consecutive range, or a custom set).
3. Create a new PdfDocument instance.
4. Retrieve the specified pages from the source document and insert them into the new document.
5. Save the new document and release resources.

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2. Splitting Each Page into a Separate PDF

If you need to save each page of a PDF as an independent file, PdfDocument.Split is the simplest method.

Method Signature

public void Split(string destFilePattern, int startNumber);

• destFilePattern: Output file path pattern; must contain the {0} placeholder, e.g., "C:\\out\\page_{0}.pdf".
• startNumber: Number for the first file; typically set to 1 (creates files like page_1.pdf, page_2.pdf, …).

Example

using Spire.Pdf;

namespace SplitPdfDemo
{
    internal class Program
    {
        static void Main(string[] args)
        {
            // Load the source PDF
            PdfDocument pdf = new PdfDocument();
            pdf.LoadFromFile("Sample.pdf");

            // Split each page into a separate file, numbering starts at 1
            pdf.Split("Output/Page_{0}.pdf", 1);

            pdf.Close();
            Console.WriteLine("Splitting completed. Each page has been saved in the Output folder.");
        }
    }
}

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3. Grouping Pages by Fixed Size

When you need to merge every N pages into one PDF (e.g., every 3 pages as a single file), Split cannot be used directly. Instead, you must manually work with PdfDocument page insertion.

Approach

1. Load the source document.
2. Calculate the number of groups: (totalPages + pagesPerGroup - 1) / pagesPerGroup.
3. For each group, create a new PdfDocument and copy the corresponding page range from the source.
4. Save the new document.

Code Example

using Spire.Pdf;
using System;

namespace SplitPdf
{
    internal class Program
    {
        static void Main(string[] args)
        {
            string inputFile = "sample.pdf";
            int pagesPerGroup = 3;                     // every 3 pages as one PDF
            string outputPattern = "Group_{0}.pdf";

            // 1. Load the source document
            PdfDocument source = new PdfDocument();
            source.LoadFromFile(inputFile);

            int totalPages = source.Pages.Count;
            int groupCount = (totalPages + pagesPerGroup - 1) / pagesPerGroup;

            // 2. Create a new document for each group
            for (int g = 0; g < groupCount; g++)
            {
                PdfDocument groupDoc = new PdfDocument();

                // Calculate start and end indexes for the current group (0-based)
                int startIdx = g * pagesPerGroup;
                int endIdx = Math.Min(startIdx + pagesPerGroup - 1, totalPages - 1);

                // Copy pages
                for (int i = startIdx; i <= endIdx; i++)
                {
                    groupDoc.InsertPage(source, source.Pages[i]);
                }

                // Save the current group
                string outputFile = string.Format(outputPattern, g + 1);
                groupDoc.SaveToFile(outputFile);
                groupDoc.Close();
            }

            source.Close();
            Console.WriteLine($"Splitting completed. Every {pagesPerGroup} pages have been merged into one file.");
        }
    }
}

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4. Other Common PDF Splitting Scenarios

4.1 Extract Specific Non‑Consecutive Pages

For example, extract only pages 2, 5, and 7:

PdfDocument source = new PdfDocument();
source.LoadFromFile("Sample.pdf");

PdfDocument result = new PdfDocument();
int[] wanted = { 2, 5, 7 };
foreach (int p in wanted)
{
    if (p >= 1 && p <= source.Pages.Count)
        result.InsertPage(source, source.Pages[p - 1]); // note: pages are 0‑based
}
result.SaveToFile("Extracted.pdf");

result.Close();
source.Close();

4.2 Extract All Odd or Even Pages

PdfDocument source = new PdfDocument();
source.LoadFromFile("AnnualReport1.pdf");

PdfDocument oddPages = new PdfDocument();
PdfDocument evenPages = new PdfDocument();

for (int i = 0; i < source.Pages.Count; i++)
{
    if (i % 2 == 0)      // 0‑based index: 0 → page 1 (odd)
        oddPages.InsertPage(source, source.Pages[i]);
    else
        evenPages.InsertPage(source, source.Pages[i]);
}

oddPages.SaveToFile("OddPages.pdf");
evenPages.SaveToFile("EvenPages.pdf");

oddPages.Close();
evenPages.Close();
source.Close();

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5. Summary

Requirement	Implementation	Core API
Each page as a separate file	pdf.Split("pattern_{0}.pdf", 1)	Built‑in Split
Every N pages merged into one file	Manual loop + InsertPage	PdfDocument.InsertPage
Extract specific pages	Manual filtering + InsertPage	Same as above

All code has been tested in real projects and can be reused directly.