SplitPDF / By file size
Split PDF by file size
The upload portal says 10 MB, your scan is 46 MB. Set a limit and SplitPDF packs whole pages into as few parts as possible, each one measured to stay under it.
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Common size limits
| Where it's going | Stated limit | Safe target |
|---|---|---|
| Gmail attachment | 25 MB per message | 15–18 MB |
| Outlook.com / Microsoft 365 attachment | 20 MB (org settings vary) | 12–14 MB |
| Yahoo Mail | 25 MB per message | 15–18 MB |
| Job, visa and university portals | often 2, 5 or 10 MB per file | just under the stated number |
Email attachments are encoded as base64 in transit, which makes them about 33% bigger. That's why a 20 MB file can bounce from a "25 MB" mailbox. Limits are those published by each provider and can change.
How size-based splitting packs pages
A 16-page scan (35.0 MB) where photo pages are much heavier than text pages. Move the limit.
6 files. Pages are kept in order and never cut, so a file closes as soon as the next page would push it over the limit. Page 14 alone is 12.4 MB, bigger than your limit: it ends up in a file on its own and still breaks it (red). Splitting can't fix one heavy page; only compression can.
Questions about size-based splitting
How do I split a PDF to fit an email attachment limit?
Choose a limit below your provider's cap (10–15 MB is safe for Gmail and Outlook), press Split PDF and send each part in its own email.
Why are my parts smaller than the limit?
Pages are never cut, so a part closes as soon as the next whole page would push it over. If one heavy page follows, the part may end well under the limit.
One page is bigger than my limit. What can I do?
Splitting cannot make a single page smaller. Compress the PDF (which lowers image resolution) or pick a higher limit. SplitPDF tells you which pages are too big.
Is the size exact?
Yes. Each part is actually built and measured before it's accepted, rather than estimated, so the file you save is the size shown.
Is splitting better than compressing?
Splitting keeps full quality; compressing keeps one file. For contracts and scans you need to stay legible, splitting is the safer choice.