Organize PDF · guide
What Split PDF by size or bookmark does
Split PDF by size or bookmark divides a PDF automatically, so you do not have to work out page numbers: every N pages, into N equal parts, around a file size, at each top-level bookmark, at blank separator pages, or wherever a page starts with text you name. Pages are copied without being re-encoded, the notes under the result explain every cut, and the document is never uploaded.
How to split PDF by size or bookmark in your browser
- Choose one PDF Select the PDF to divide. It opens in this browser tab and is not uploaded.
- Choose how to split Pick a method: Every N pages, Into N equal parts, Around a file size, At bookmarks, At blank pages or At page-start text, then enter the number, size or text it asks for.
- Split and save Select Split the PDF, read how many files were made and the notes under the result, then save them one by one or with Save all (ZIP). When splitting at blank pages, the blank separators themselves are left out.
Worked example
Divide a 60-page training handbook into six smaller packets.
- Starting point
- Choose the handbook PDF and confirm it contains 60 pages.
- What to do
- Select Every N pages and enter 10. Review the selected mode before creating the pieces.
- Result
- Expect six PDFs of ten pages each. With 63 source pages, the last piece would contain the remaining three pages.
If the result is not right
If page-start text finds no boundaries, check that the phrases start the relevant pages and that the PDF has a text layer. OCR an image-only scan first.
Limits worth knowing
- File-size splitting is approximate: a single oversized page cannot be split into less than one page. Bookmark and text modes depend on document structure. Links that jump to another page may not work in the results, so click through any you rely on.
- This workflow stops on interactive forms rather than risk losing their fields. Use Flatten first and check every visible answer in that saved copy, then open the flattened PDF here. Keep the editable original; protected or XFA forms may need a compatible form application first.
Questions and answers
Can I split a PDF to fit an email or upload size limit?
Yes: choose Around a file size, enter the limit and pick MB, KB or bytes, where 1 MB is 1,000,000 bytes. Because pages share fonts and images, the tool builds candidate files and measures them rather than guessing, then reports the largest and smallest file it made; on a very long document it estimates the later cuts and says from which page. A page bigger than the limit on its own still becomes its own file, and the result says so. If the whole PDF already fits, it tells you instead of splitting.
Why do the split files add up to more than the original?
A font or image that several pages share is stored once in the original, but every new file that uses it needs its own copy, so the pieces together can come to several times the original's size. A piece can also carry hidden copies of pages it links to, or images and drawings it shares with other pieces. The notes under the result say when this has happened.
How do I split a PDF into chapters?
If the PDF has bookmarks, choose At bookmarks. Each top-level bookmark starts a file named after it and numbered in reading order, sub-bookmarks are ignored, and any pages before the first bookmark become a first file labelled Front matter. If the PDF has no usable bookmarks, At page-start text cuts at each page whose opening text contains words you give, such as Chapter. To cut a long book into parts of equal length instead, such as 20 pages to read at a time, choose Every N pages and enter 20: a 310-page book becomes 16 files, the last with 10 pages. A chapter file that is still too long can be run through Every N pages again.
Why did At page-start text cut in the wrong places, or miss a heading?
It reads the first 900 characters of each page's text layer and cuts wherever one of your phrases appears there, ignoring capitals. A heading low on a busy page can fall outside that window, a reworded heading will not match, and a scanned page has no text to read until it has been through OCR PDF. A running header that repeats your word on every page cuts at every page, so choose a phrase only the first page of each document carries. Separate several phrases with commas.
What counts as a blank page?
A page that is almost entirely white when drawn at low resolution on your device, so faint scanner noise does not stop a separator sheet counting. Blank separators are left out of the pieces, and there must be at least two non-blank sections to split. Check the result, because a page with very little on it can be read as blank too.
How does Into N equal parts share out pages that do not divide evenly?
The extra pages go one each to the first files, so 49 pages in 5 parts gives four files of 10 pages and one of 9, never a last file of 13. Every N pages works the other way: each file has N pages and the last has whatever is left. N has to be smaller than the page count, and a one-page PDF cannot be split.