How to Split PDF By Bookmarks
Splitting a PDF by its bookmarks is the most efficient way to break a large document into logical sections — each bookmark becomes a separate file. This is invaluable for distributing individual chapters of a book, separating sections of a policy manual for different departments, or extracting specific parts of a lengthy report. SublimePDF reads the bookmark structure and splits at each top-level bookmark automatically.
Follow the step-by-step instructions below, then use the free tool directly — no registration or download required.
Open Tool →How to Split PDF By Bookmarks — Step by Step
Upload your bookmarked PDF
Upload a PDF that contains bookmarks (also called an outline or table of contents). The tool reads the bookmark tree and displays it for your review.
Review the bookmark structure
SublimePDF displays all bookmarks in a tree view. Verify the bookmark hierarchy — top-level bookmarks typically correspond to chapters or major sections.
Choose split level
Select whether to split at top-level bookmarks only (chapters), second-level bookmarks (sub-sections), or all bookmark levels. Top-level splitting is the most common choice.
Configure output naming
Choose how output files are named: by bookmark title (Chapter-1-Introduction.pdf), by sequential number (part-01.pdf), or a custom prefix with sequential numbers.
Split and download
Click split to generate separate PDF files for each bookmark section. Download them individually or as a ZIP archive containing all parts.
Pro Tips
- 💡 Before splitting, open the PDF in any viewer and check the bookmarks panel to verify the document actually has bookmarks. PDFs without bookmarks can only be split by page numbers.
- 💡 If the PDF has a multi-level bookmark hierarchy, split at the top level first. You can always split the resulting files further if needed.
- 💡 Use descriptive bookmark titles — they become the output file names. Clean up bookmark text before splitting if it contains special characters or is truncated.
- 💡 For large manuals or textbooks, splitting by bookmarks creates a ready-made file structure that maps directly to the table of contents.
Privacy & Security
All processing happens directly in your browser. Your files are never uploaded to any server — they remain on your device throughout the entire process. SublimePDF uses WebAssembly technology for fast, secure, client-side processing.
Works Everywhere
This tool works on any modern browser — Chrome, Firefox, Safari, or Edge — on desktop, tablet, or mobile. No software to install. PDF is an open ISO standard supported by all major platforms.
How to Split PDF By Bookmarks — FAQ
What if my PDF doesn't have bookmarks?
Can I split at second-level bookmarks?
Are bookmarks preserved in the split files?
How are output files named?
Related Guides
How to Split PDF Pages
Need to extract specific pages from a large PDF or split a document into separate files? SublimePDF's Split PDF tool makes it easy — select your pages and download instantly.
How to Split PDF Every N Pages
Splitting a large PDF at regular intervals is invaluable when you have a combined document that follows a repeating structure — such as monthly reports where each report is exactly 4 pages, multi-student grade sheets with 2 pages per student, or batch-scanned forms with a fixed page count. Instead of manually selecting page ranges, splitting every N pages automates the process and produces uniformly sized output files in seconds.
How to Split PDF By File Size
Email attachment limits, upload form restrictions, and storage quotas often require splitting a large PDF into smaller chunks that each fit under a maximum file size. Splitting by page count alone doesn't guarantee size — a 10-page PDF with high-res photos on pages 3-5 may produce unevenly sized parts. SublimePDF's size-based split divides a PDF into parts that each stay under your specified limit.