Split a PDF File

Three ways to split a PDF

The settings panel has three tabs, each built for a different job:

• Range cuts the document into page ranges. "Custom" lets you type exact ranges such as 1 to 3 and 7 to 12. "Fixed" chops the file into equal blocks, for example every 5 pages. "Smart" separates odd and even pages into two files.
• Pages turns pages into individual PDFs. "Extract All" saves every page as its own file; "Select Pages" lets you click only the pages you want, and each selected page becomes a separate PDF.
• Size splits the document into parts that each stay under a maximum file size you choose, in KB or MB.

Which mode should you use?

How page ranges are counted

Page numbers start at 1 and both ends of a range are included, so "3 to 5" gives you pages 3, 4 and 5. A range that runs past the last page is simply cut at the end of the document. Each range becomes its own PDF unless you tick "Merge all ranges into one PDF file", in which case the ranges are joined in the order you listed them. That makes the merge option a handy way to re-order sections as well: list "10 to 12" before "1 to 3" and the new file starts with page 10. The preview under the ranges shows exactly which pages will land in which file before you press "Split PDF".

Splitting by file size

In the Size tab the tool walks through the document page by page and keeps adding pages to the current part until the next page would push it over your limit; then it starts a new part. Pages are never cut or re-compressed, so a single page that is larger than the limit on its own (a high-resolution photo, for example) will become its own part and can still exceed it. For upload forms, set the limit a little below the real maximum, for example 9.5 MB for a 10 MB limit, to leave room for rounding differences between systems.

The optional "Allow compression" setting stores the PDF's internal structure more compactly. It is lossless: it does not touch the quality of text or images, it just removes some overhead, which often makes each part slightly smaller.

What you download

If the split produces a single file you get that PDF directly. Several files are packed into one ZIP archive so your browser doesn't ask you to approve a dozen separate downloads. The files are named after the original document with a clear suffix such as _range1, _page_7 or _part2, so you always know what each file contains.

Quality and privacy

Splitting copies the original pages into new documents with pdf-lib, an open-source PDF library that runs inside your browser. Text remains selectable, images keep their resolution and nothing is uploaded to a server. Password-protected files need to be unlocked in a PDF reader first. If you are sorting double-sided scans, our guide to odd and even pages explains the Smart mode step by step.