Split PDF by file size
Split a PDF into multiple files, each kept under a target file size.
The split PDF by file size tool packs a document's pages into multiple output files, each kept under a target size you choose in megabytes — useful when you need to fit a PDF under an email attachment limit or a form's upload size cap, without worrying about which specific pages to put where.
Click to choose a PDF, or drag one in here
One file at a time
How to use
- Upload a PDF file and set your target maximum size per output file, in megabytes.
- Click "Split & download" — pages are packed into files that each stay under your target size where possible.
Common use scenarios
- Splitting a large PDF so each part fits under an email attachment size limit.
- Breaking a document into pieces that fit an upload form's file size cap.
- Preparing a large scanned document for sharing across a size-limited channel.
- Dividing a big report into smaller, more manageable files by size rather than by page count.
✓Content & verification reviewed: 2026-08-25
How we verify Split PDF by file size
How to confirm the split output files match your target size.
Each output file stays at or under your target size where possible
Pages are packed one at a time into the current output file, and a new file starts as soon as adding the next page would push it over your target size — so the number of output files depends entirely on your content and target size, not a fixed page count.
A single oversized page still gets its own file
If one page alone is larger than your target size (a page with large embedded images, for example), it's still output as its own file since there's no way to split a single page further — that file will exceed your target size.
Processing time scales with document length
The tool re-saves the working document after adding each page to check its actual size, so a document with many pages takes proportionally longer to process than a short one.
Before you rely on the result
- Your target size accounts for the destination's actual limit, with a bit of margin if needed.
- You've checked whether any single-page output exceeded your target due to an oversized individual page.
- You've allowed extra processing time for documents with a large page count.
- You've downloaded and verified the resulting files' sizes before relying on them fitting a hard limit.
Who this is for
- Anyone splitting a large PDF to fit under an email attachment size limit.
- People breaking a document into pieces for a size-limited upload form.
- Anyone preparing a large scanned document for sharing across a constrained channel.
- People dividing a big report into files by size rather than by page count.
Real-world examples
Fitting an email attachment limit
Someone splits a large PDF report into several smaller files, each under their email provider's attachment size limit, before sending it.
Meeting an upload form's size cap
A person splits a large scanned document into parts that each fit under a government or institutional form's upload size limit.
Sharing a large scan over a constrained channel
Someone splits a bulky scanned PDF into smaller pieces to share over a messaging app with a strict file size limit.
Limitations
- A single page that alone exceeds your target size is still output as its own file, since a page can't be split further.
- Works by repeatedly re-saving the document while checking its size, so very long documents can take a while to process.
Frequently asked questions
How many output files will I get?
That depends entirely on your document's content and your target size — the tool packs as many pages as fit under the target into each file, so the count isn't predictable in advance.
What happens if a single page is bigger than my target size?
It's still output as its own file, since a page can't be split further — that particular file will exceed your target size.
Why is this slower than the range-based split tool?
This tool re-saves the document after every page to check its actual size, which takes more processing than splitting by pre-defined ranges — longer documents take proportionally longer.
Does this upload my PDF anywhere?
No — splitting happens entirely in your browser using pdf-lib; the file is never sent to a server.
🔒 Runs in your browser — nothing is uploaded. Results are for reference only; see the disclaimer. Last updated: 2026-08-25
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