Split PDF by File Size
Split a PDF by file size when it’s too big to send in one go: type the limit — 25 MB for Gmail, 2 MB for a job portal — and get as few parts as possible, each one under it.
Where is this PDF going?
Fit Meter
Settings appear once you add a PDF.
Still going. Your own device is doing this, so a long scan or a big batch takes as long as it takes — and none of it is being uploaded.
Bytes of your files sent anywhere: 0 B · nothing leaves this tab
Every request this page makes is listed as it happens. You’ll see our own code loading, and for some formats a codec engine, but never your file going out.
- Waiting for network activity…
Check it yourself: open your browser’s developer tools on the Network tab, or turn off Wi-Fi once the page has loaded. The tools keep working.
How to split a PDF by file size
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Add your PDF
Drop the big PDF.
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Check the settings
Pick where it’s going — Gmail, Outlook, a portal — or type your own limit.
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Save the result
Save the parts. Each holds as many whole pages as fit under the limit, so you send the fewest files.
Why it doesn’t upload
A PDF too big to email is usually a big scan — a whole application, a year of statements. Splitting it here means the full file never has to be uploaded, which is the very thing its size makes slow.
Check it in your browser’s Network tabWorth knowing
- A single page bigger than the limit can’t be split further; it goes in its own part and is flagged. Compress the PDF first to fix that.
- Parts are split at page boundaries — a page is never cut in two.
- Shared fonts and images are included in every part that needs them, so the parts add up to a little more than the original.
Under the hood
What happens to your file
To keep each part under a size limit, the tool saves candidate parts and measures them, using a galloping then binary search over page counts — so a 300-page file needs a few dozen trial saves, not three hundred. Pages are never recompressed to fit; a single page larger than the limit is reported, not squeezed.
Reference: pdf-lib documentation
Questions
How do I split a PDF into parts under 10 MB?
Type 10 MB as the limit (or pick a destination) and press Split by size. You get the fewest possible parts, each under 10 MB.
How do I email a PDF that’s too large?
Pick Gmail or Outlook as the destination and split it into parts that each fit, then send them in separate emails. Or make it smaller with a compressor first.
Why is one part still too big?
Because one page on its own is bigger than the limit — usually a high-resolution scan. Compress the PDF first, then split.
Does splitting by size lose quality?
No. Pages are copied exactly; the tool only decides where one part ends and the next begins.