Merging & Organizing
How to Split a PDF by File Size
Break an oversized PDF into pieces that fit an email or upload limit — how to work out the split points and when to compress instead.
Some limits cannot be argued with: a 25 MB email attachment cap, a portal that rejects anything over 10 MB, a filing system with a hard ceiling. When a document is over the line, you either make it smaller or you cut it into pieces.
Try compression first
A split document is worse for the reader — several files to keep track of, in the right order, opened separately. If compression gets you under the limit, that is the better answer, and on scanned documents it usually does: reductions of 60–90% are routine, because scans are images and images compress hard.
Split when the file is genuinely large after compression, or when the pieces are naturally separate documents anyway.
Working out where to cut
- 1Note the file size and the page count.
- 2Divide to get a rough size per page — a 60 MB, 120-page file averages 0.5 MB a page.
- 3Divide the limit by that figure and take a margin. For a 10 MB cap at 0.5 MB a page, aim for 16 pages rather than 20.
- 4Split by those ranges, then check the actual sizes of the results.
- 5Adjust and re-split if one part came out over. Pages are rarely uniform in size.
Split at meaningful boundaries where you can
Cutting a document mid-sentence to hit a size target makes it hard to read. Where the content has natural joints — chapters, sections, individual invoices in a batch — split there and accept slightly uneven file sizes. Name the parts clearly, and say in your covering message how many there are and in what order.
Better alternatives to splitting
| Option | When it is the right call |
|---|---|
| Compress the PDF | Almost always worth trying first, especially for scans |
| Share a link instead | When the recipient can accept a cloud link |
| Send only the pages needed | When the recipient asked for one section, not the whole pack |
| Split into parts | When the limit is hard and the whole document must go |
Extracting the pages someone actually asked for is frequently the real answer. A twelve-page extract beats four numbered parts of a hundred-page document that nobody will read in full.
Do it now
Split PDF
Separate a PDF into individual pages. It runs in this browser tab — your file is not uploaded anywhere.
Open Split PDFFrequently asked questions
Can I split a PDF into equal file sizes automatically?+
Not precisely, because pages vary enormously in size. Estimate from the average, split by page ranges, then check and adjust.
What is the usual email attachment limit?+
Gmail and Outlook both cap at around 25 MB, and many corporate servers are stricter — 10 MB is a common internal limit. Aim comfortably under whichever applies.
Do the split parts add up to the original size?+
They usually total slightly more, because each part carries its own copy of the fonts its pages use.
Is compressing better than splitting?+
Nearly always, for the reader. One file that opens is better than four that have to be reassembled mentally.