How to Split a Large PDF into Smaller Files

Big PDFs cause small headaches. Email bounces it back as too large, the upload form rejects it, or it takes ages to open on a phone. Splitting the document into smaller files is usually the quickest fix, and it only takes a minute once you know how many pieces you need.

This guide shows how to work out the right number of parts, how to split a PDF for free on any device, and what to do when splitting alone isn’t enough.

Why large PDFs get rejected

Most email services limit the total size of attachments on a message, typically somewhere around 20–25 MB, and the recipient’s inbox may have a lower limit than yours. Online forms are often stricter still: job portals, visa and government applications, insurance claims and university systems commonly cap uploads at a few megabytes per file, or ask for one document per upload box.

Scanned documents are the usual culprits. A single scanned page in color at high resolution can easily weigh more than a megabyte, so a 50-page scan can be tens of megabytes even though it’s “just paperwork”.

Step 1: work out how many parts you need

Split by pages, but plan by size. A simple calculation gets you close:

1. Note the file size and page count. In our tools, both appear as soon as you open the file.
2. Divide the size by the number of pages to get the average size per page.
3. Divide the limit you’re aiming for by that average, and round down to leave some headroom.

Example: a 48 MB scan with 96 pages averages 0.5 MB per page. To stay under a 20 MB email limit, aim for parts of around 30 pages (about 15 MB each). That gives you four files: pages 1–30, 31–60, 61–90 and 91–96.

Pages aren’t all the same size (a photo-heavy page weighs more than a page of text), so check the size of each part after splitting, and split again if one is still too large.

Step 2: split the PDF

In your browser, on any device

PDFCocoon’s Split PDF tool runs in your browser and never uploads your document, which is useful when the big file is a medical record or a set of financial statements.

1. Open Split PDF and drop in your file.
2. Choose Every N pages and enter the number you calculated, such as 30. Or choose Custom ranges and type them, such as 1-30, 31-60, 61-96, to split at chapter or document boundaries instead.
3. Check the list of files that will be created, then press Split.

The parts download together in one ZIP file, each named after its pages (for example scan-pages-31-60.pdf), so they stay in order and it’s obvious what each one contains.

Built-in options on Mac, Windows and phones

Every major platform can save a range of pages as a new PDF through its print screen. On a Mac, use File → Print in Preview, enter a page range and choose Save as PDF. On Windows, print from Microsoft Edge to Microsoft Print to PDF with a custom page range. On Android, print to Save as PDF with a range.

The catch is that you have to repeat the whole process once for every part, and printing redraws the pages, which can break links and sometimes makes files bigger. That’s the opposite of what you want here, so a dedicated split tool is usually the better choice.

When splitting isn’t enough

A single page is still too big

If one page is over the limit on its own, splitting can’t help. That usually means a very high-resolution scan. Rescanning at 200–300 DPI, and in grayscale for plain text documents, typically shrinks pages dramatically while staying perfectly readable.

You need one file, not several

Some forms insist on a single document. Remove anything that isn’t required (cover sheets, blank backs, duplicate pages) with Delete PDF Pages, or keep only the essential pages with Extract PDF Pages. Rebuilding the document from fewer pages often brings it under the limit.

Email just won’t take it

For very large documents, a link from a cloud storage service you already use can be simpler than several emails. Just remember that a link gives access to whoever has it, so share it carefully.

Sending split files professionally

• Number your emails: use subjects like “Application documents (1 of 3)” so the recipient knows to expect more.
• Keep the names meaningful: “smith-medical-records-pages-1-30.pdf” beats “Part1.pdf”.
• Say what’s in each part: a one-line list in the first email saves everyone time.
• Double-check before sending: open each part to confirm it starts and ends where you expect.

Putting it back together

If you or the recipient need the full document again later, the parts can be recombined in order with Merge PDF. Because the pages were copied rather than printed, nothing is lost along the way.