Split PDF

How do you split a PDF into separate files?

Choose your PDF, select how the pages should be grouped, then click Split PDF. Each page creates an individual document for every source page. Every N pages makes consecutive groups, while Custom ranges lets you choose exactly which pages belong in each output. Download each PDF separately or collect multiple outputs with Download All (.zip).

For a 12-page source, these settings produce different results. Page ranges are inclusive: both the first and last page belong to the range. Choose based on the documents you need, rather than splitting every page and manually assembling the pieces afterward.

Outputs from a 12-page PDF

Setting	Output files	Pages in each output
Each page	12 PDFs	One source page per file
Every N pages, with N = 5	3 PDFs	1-5; 6-10; 11-12
Custom ranges: 1-3, 7, 10-12	3 PDFs	1-3; 7; 10-12
The same ranges, combined	1 PDF	1, 2, 3, 7, 10, 11, 12

How does PDF splitting work?

A PDF organizes pages through a page tree, defined in the ISO 32000 PDF specification. This tool uses pdf-lib to load the source, create new PDF documents, copy the chosen pages and save the results. It copies page objects rather than rendering each page as a screenshot. Page content such as text, images and vector graphics is therefore handled as PDF content.

The split operation does not copy the source document's bookmark outline into the new documents. Bookmark splitting uses that outline to choose boundaries and output names instead. Check navigation links in the saved parts: a destination page placed in a different output is no longer available within that part. Keep the original document when its complete navigation structure matters.

Which split mode should you choose?

• Each page creates one PDF per source page, useful for filing individually scanned records.
• Every N pages creates consecutive groups of the entered size. The last group contains any remaining pages.
• Custom ranges creates a PDF for each comma-separated page or inclusive range. Check Combine all ranges into one file to make a single extraction instead.
• Bookmarks / chapters uses existing outline destinations to divide the document into chapters.
• Maximum file size groups consecutive pages using the size of saved PDFs, with an exception for an oversized single page.

Custom ranges does not automatically keep unselected pages. Save the original if you might need them later. For overlapping ranges, separate outputs each contain the pages requested for that range; the combined option removes repeated pages while keeping their first occurrence in the entered order.

How do previews and page selection help?

The page preview shows thumbnails and colored partitions for page-based and bookmark splits. In Custom ranges, click a thumbnail to select or deselect its page. Odd pages selects physical pages 1, 3, 5 and so on; Even pages selects 2, 4, 6 and so on. Invert selection chooses all pages currently left out.

Thumbnail clicks and selection shortcuts rewrite the range field in ascending page order. If you need a different sequence, type the ranges yourself afterward. Use the source page positions, not printed page labels inside a report. Invalid syntax, reversed ranges, page 0 and page numbers past the source count prevent splitting until corrected. Size-based boundaries are determined during processing rather than shown as a final partition preview.

How do you split a PDF by bookmarks or chapters?

Choose Bookmarks / chapters, then use Bookmark level to include top-level entries alone or nested bookmarks as well. Available level choices stop at 4. Only entries with usable destinations contribute boundaries, and multiple bookmarks on the same page produce one boundary. The first chapter begins at the first source page, so introductory material before the earliest bookmark stays in the first output.

Chapter outputs use bookmark titles in their filenames. Unsafe filename characters are replaced, and repeated titles receive a numbered suffix. A PDF without usable bookmarks shows No bookmarks found and disables this mode. Use Custom ranges when the document has visible chapter headings but no bookmark outline; the tool does not infer chapters from heading text.

How do you split a PDF to fit a file size limit?

Maximum file size accepts a positive MB value. The conversion uses 1,048,576 bytes per MB. The engine first saves individual pages to estimate grouping, then measures saved candidate parts and adjusts their page counts. It keeps consecutive source pages together and advances through the document without omitting pages.

A single page that exceeds the chosen limit is output alone and marked over the limit. Splitting changes page grouping; it does not compress images or cut a page into smaller pieces. Review the saved sizes before sending attachments, and leave room for any additional constraints imposed by the receiving system.

How are split files named and downloaded?

The filename field appears after splitting. For ordinary splits, setting the base name to contract gives contract-part1.pdf, contract-part2.pdf and subsequent part numbers. Bookmark mode uses base-Chapter title.pdf instead. Each result lists its page count and size alongside a Download button.

When there is more than one output, Download All (.zip) collects the parts with their PDF filenames. A single combined extraction has an individual download instead. To assemble parts again, use Merge PDF. To discard pages while keeping the remainder together, consider Delete PDF Pages.

When is splitting useful?

Extract relevant contract pages for review, separate records from a combined scan, or prepare selected pages for printing. Choose chapter boundaries when the source already has useful bookmarks. Choose a size limit when the receiving system restricts individual files. These workflows need different grouping rules, so check both the selected pages and the number of resulting files.

How do you verify private, browser-based processing?

The source file is read with the browser's file API, and splitting creates PDF bytes and downloadable blobs locally. The Content Security Policy permits connections only to this site. This is a connection restriction, while the splitting implementation itself makes no network call to upload the PDF. Inspect the browser's Network panel during a split to check for file transfers.

Local processing still needs the application code to load. Avoid assuming that an open page guarantees every required resource is already available offline. The tool also has no password entry or decryption step: the split operation loads PDFs without an encryption override. Use an unlocked source PDF before splitting.

How do you handle large PDFs within browser memory?

The application holds source bytes, generated PDF blobs and, for multiple outputs, a ZIP blob in memory. It displays a memory warning when its warning hook identifies risk. There is no fixed processing-time promise: document content, output count and device resources all affect the work required. Creating many individual files also creates many output blobs.

Extract only the ranges you need when you do not require every page. For a document that strains your device, try fewer outputs per operation and retain the source for another pass. Check the results before closing the page. Splitting is a grouping operation, so it does not guarantee that the combined size of all outputs will be smaller than the original PDF.