Got a textbook, manual or report as one long PDF? How bookmark splitting turns each chapter into its own file, and the fallback for PDFs without bookmarks.

To split PDF by chapters, upload the book or report to ToolistHub's free Split PDF tool and choose By Bookmarks, an option that appears only when the PDF has bookmarks. You get one file per chapter without typing a single page number. If the option is missing, the PDF has no bookmarks, and you can split it with page ranges taken from the table of contents instead.

Check whether your PDF has chapter bookmarks

Bookmarks are the clickable outline that some PDFs carry: a list of chapter titles that jump to the right page. Whether a PDF has them depends on how it was made, so check before you plan the split.

The quickest way to check is to upload the PDF to Split PDF: the By Bookmarks option appears under Split Options only when the file has bookmarks, so the option itself is your answer. If it isn't there, skip to the page-range method below.

How to split a PDF by chapters with bookmarks

Open Split PDF and upload the PDF. It can be up to 4 MB and 500 pages.
If the PDF is password-protected, type the password once and choose Submit Password.
Under Split Options, choose By Bookmarks. There is nothing else to fill in.
Leave Output Format on ZIP Archive and choose Split PDF.
Choose Download Results, then unzip the file to get one PDF per chapter.

How the bookmark split decides where each chapter starts

One file per top-level bookmark

The split follows the top level of the outline. Each top-level bookmark starts a new file that runs until the page before the next one, and the last runs to the end of the PDF. The files follow page order, and if two bookmarks point to the same page, that page starts only one file.

Bookmarks nested inside a chapter, such as section headings, don't create files of their own: their pages stay in the chapter's file. If the top level lists parts (Part I, Part II) rather than chapters, you get one file per part, and page ranges are the way to cut those parts into chapters.

Pages before the first bookmark (cover, contents, preface)

If the first bookmark starts after page 1, the pages before it, usually the cover, contents and preface, become an extra first file called Start. Keep it with the chapters or set it aside if you don't need the front matter.

How the chapter files are named

Each file name joins the original name, the bookmark title and a part number. The title is cut to 30 characters and loses symbols such as colons, so in biology.pdf a bookmark called Chapter 1: Cells becomes biology_Chapter 1 Cells_part_2.pdf when a Start file comes first. The ZIP itself is called biology_split.zip.

No bookmarks? Split PDF by chapters with page ranges

Without bookmarks, the table of contents does the same job. Note the page where each chapter starts, then choose By Page Range and type one entry per chapter: 1-18, 19-40, 41-63 gives you three files.

Check one thing first: the page numbers printed in a book often differ from the PDF's own page numbers, because the cover, contents and preface come first. If chapter 1 is printed as page 1 but is the 13th page of the PDF, add 12 to every number in the contents. The page previews are labelled with PDF page numbers, which helps you confirm the offset within the first 24 pages.

Page-range files are named biology_part_1.pdf, biology_part_2.pdf and so on, in the order you typed the ranges, so rename them with the chapter titles afterwards. The guide on how to split a PDF by page range explains the format in more detail.

Limits to check before you split a book

4 MB and 500 pages: books with many images can be larger than the 4 MB upload limit, and a PDF of more than 500 pages can't be split at once.
Results over about 4 MB are refused: if the chapter files together come to more than that, the tool says so. Split a few chapters at a time with page ranges instead.
Sections inside chapters stay together: only top-level bookmarks start new files.
Books made from scans stay images: they split normally, but ToolistHub can't make their text selectable.
Links between chapters: a contents page or cross-reference that jumps to another chapter can't take you there once that chapter is in a different file.
Copyright still applies: splitting a textbook doesn't change who owns it, so share chapters only where you have the right to, such as within a course that allows it.

What to do with a chapter after splitting

Edit it in Word. Upload the chapter to ToolistHub's PDF to Word converter. Its default editable mode converts the selectable text and images, but tables are not rebuilt as Word tables, so check them. A chapter is much shorter than the whole book, which makes the result easier to review. If the Word file looks wrong, the guide to why a PDF won't convert to Word properly explains the common causes and fixes.

Summarize it. Copy the chapter's text into the AI Text Summarizer, choose Paragraph, Bullet Points or Key Takeaways, and add a focus such as key terms or dates. For a very long chapter, summarize one section at a time. The text is sent to Google's Gemini API, and AI summaries can contain mistakes, so check the summary against the chapter before you study from it.

Frequently asked questions

How do I separate chapters in a PDF?

If the PDF has bookmarks, upload it to ToolistHub's Split PDF and choose By Bookmarks to get one file per chapter. If it doesn't, type each chapter's page range under By Page Range, using the table of contents.

How do I split a PDF by bookmarks?

Upload the PDF to Split PDF. When it has bookmarks, a By Bookmarks option appears under Split Options; choose it, select Split PDF and download the ZIP with one file per top-level bookmark.

Can I split a PDF into chapters automatically?

Yes, if the PDF has chapter bookmarks: By Bookmarks finds where each chapter starts. ToolistHub doesn't look for chapter headings in the text itself, so a PDF without bookmarks needs page ranges.

How do I split a PDF book into chapters?

Upload the book to Split PDF and look for By Bookmarks. If it's there, choose it; if not, take the chapter start pages from the contents, adjust them for the front pages and type them as ranges such as 1-18, 19-40.

Conclusion

Splitting a book by chapters takes one choice when the PDF has bookmarks, and a few minutes with the table of contents when it doesn't. Upload it to ToolistHub's free Split PDF tool, look for By Bookmarks, and fall back to page ranges if it isn't there.

Split PDF by Chapters: Use Bookmarks or Page Ranges