A long PDF that was made properly already knows where its own divisions are. The bookmarks panel in a reader shows them: chapters of a book, sections of a report, each statement in a year of statements. Splitting by page numbers means reading that list, writing the numbers down and typing them out, and any mistake silently moves a boundary. This tool reads the bookmarks itself and cuts where they start, so each section comes out as its own PDF named after the heading it begins with.
How to use Split by Bookmarks
- Add the PDF. It needs bookmarks already in it; if the bookmarks panel in your reader is empty, this tool has nothing to cut on.
- Choose the bookmark level to split at. Level 1 is the top of the contents list, level 2 is the sub-headings beneath it.
- If the file is password protected, enter its password in the PDF password field.
- Select Split by Bookmarks.
- Download the ZIP. Each section is a numbered PDF named after its bookmark, so the parts stay in reading order in any file list.
Where the cuts are made
Every bookmark at the level you choose starts a new file, and that file runs until the next bookmark at the same level begins.
- A section runs to the next heading: A bookmark on page 5 with the next one on page 12 produces a file of pages 5 to 11. The last bookmark takes everything from its page to the end of the document.
- Anything before the first bookmark: Pages that come before the first bookmark at your chosen level, typically a cover and a contents page, are not included in any section. Use Extract Pages if you need them as a separate file.
- Deeper bookmarks ride along: Choosing level 1 does not lose the level 2 headings inside a chapter. They are simply not cut on, and stay within the section they belong to.
- Two headings on one page: If two bookmarks point at the same page, the earlier section has no pages of its own and is skipped rather than producing an empty file.
Choosing the right level
The level decides how many files you end up with, and it is worth checking the bookmarks panel before deciding.
- Level 1 for chapters: In most books and reports the top level is the chapter or section list. Splitting there gives a handful of substantial files, which is what you usually want for distribution.
- Level 2 for sub-sections: Choose level 2 when the top level is too coarse, for example a manual whose level 1 is just Part One and Part Two. Expect many more, and much shorter, files.
- If the level is empty: A PDF with only one level of bookmarks has nothing at level 2, and the tool says so rather than returning an empty ZIP. Drop back to level 1 and run it again.
- One section only: If the level you pick has a single bookmark, the result is one PDF rather than a ZIP, since there is nothing to pack together.
How the parts are named and what they keep
- Named after the heading: Each file is named after your document, a two-digit position and the bookmark's own text, so annual-report-03-Financial-Review.pdf tells you what it holds without opening it.
- Numbered to stay in order: The number keeps the parts sorted the way the document reads, which matters because headings rarely sort alphabetically into the right order.
- Punctuation is trimmed: Characters a file system dislikes, such as colons and slashes, are removed from the heading, and a very long heading is shortened. The PDF inside is untouched.
- Pages are copied, not redrawn: Every page is carried across whole, with its text, images, size and rotation as they were, so nothing is re-encoded and no quality is lost.
When people use Split by Bookmarks
Sending each chapter to a different reviewer
A report with chapter bookmarks becomes one file per chapter in a single step, ready to attach to separate emails without anyone receiving the whole document.
A year of statements in one download
Bank and payroll exports often bookmark each statement by date. Splitting on that level files a year's worth in one pass.
Breaking up a manual for a help site
Each bookmarked section becomes its own PDF, named after its heading, which maps directly onto a page per topic.
Limitations to know
The PDF must already contain bookmarks. Scanned documents and files exported without an outline have none, and there is nothing for the tool to cut on; add them with PDF Bookmarks first, or split on page ranges with Split PDF. Bookmarks, form fields and attachments are not carried into the resulting sections. Pages are copied without re-encoding, so the parts add up to roughly the size of the original.
Split by Bookmarks: common questions
How do I know whether my PDF has bookmarks?
Open it in any reader and look for the bookmarks or outline panel, usually a side panel with a ribbon or list icon. If it shows a list of headings you can click to jump around, those are the bookmarks this tool reads. An empty panel means the file has none.
What happens to the cover page and table of contents?
Pages before the first bookmark at the level you chose are not part of any section, so they are left out of the result. That is usually what you want, since a cover belongs to the whole document rather than to its first chapter. If you need them, Extract Pages will save that range as its own file.
Can I split at level 2 without losing the chapter headings?
The headings are not lost, but the files are cut at every level 2 bookmark, so a chapter is spread across several files rather than kept as one. If you want chapters kept whole, split at level 1 instead.
Why did I get a single PDF instead of a ZIP?
Because the level you chose has only one bookmark, which means there is only one section to produce. A ZIP holding one file would just be an extra step, so the PDF is returned directly.
Do the resulting files keep their own bookmarks?
No. Each section is built as a new document from copied pages, and the outline is not carried across. If the parts need their own contents lists, add them afterwards with PDF Bookmarks.