How to Split a Large PDF into Separate Chapters or Files

Why split a large PDF at all

Large PDFs are hard to send, slow to open on a phone, and awkward to read when only one chapter matters. Splitting turns one heavy file into smaller files that each do one job: one chapter per file, one section per recipient, or one part per email. The original stays untouched, so you can always go back and split it differently.

Plan your ranges before you start

Open the file in your PDF reader and use the contents page, or the page numbers shown in the reader, to note where each chapter starts and ends. Writing the ranges down first — for example chapter one pages 1 to 12, chapter two pages 13 to 28 — means each range is entered once and in order, instead of by trial and error.

Split a large PDF step by step

1. Open the free Split PDF tool in your browser.
2. Enter the page range for the first chapter and download it as a separate file.
3. Repeat for each remaining chapter, giving each downloaded file a clear name such as chapter-2.pdf.
4. Open each part and check its first and last pages before you send it.

There is no split-by-size mode: split by pages instead

The Split PDF tool splits by page ranges only; it has no mode that cuts a file into, say, 20 MB pieces automatically. The workaround is simple: split by chapter or by a sensible page count, then check the size of each part. If one part is still too large to send, split that part again into smaller ranges. Pages are copied as they are, so splitting never reduces quality — a part is large because its pages are large, usually because they are scanned images.

Keeping each part under the email limit

Common attachment limits are 25 MB for Gmail, 25 MB for Outlook.com, 25 MB for Yahoo and 20 MB for iCloud. Keep each part below the limit of the service your recipient uses, and remember that the limit applies to the whole message, so an email with two attachments must fit both under it. If a single chapter is still too big after splitting, the Compress PDF tool can help when the pages are image-heavy, since it recompresses embedded JPEG images; text-only PDFs barely shrink, because there is little image data to compress.

Password-protected PDFs

Password-protected files must be unlocked first in the application that created them. Once the restriction is removed, they split like any other PDF. No PaperKit tool bypasses a password.