Split PDF by Size
Split a large PDF into parts that each fit under a size limit — perfect for email attachments.
Drop your PDF hereChoose a file to get started
Free tier supports files up to 50MB.
Processed in your browser — files never leave your device. How it works
How to Split a PDF by File Size
"Attachment too large" is one of the most common reasons a PDF doesn't get where it needs to go. Email providers cap message size, and job portals, government sites and course platforms often accept only small uploads. Splitting by size breaks a big PDF into the fewest parts that each stay under the limit you choose, without touching the quality of a single page — and the splitting happens in your browser, so the document is never uploaded anywhere.
- 1
Upload the large PDF
Add the file that's too big to email or upload. Files up to 50 MB can be split for free.
- 2
Pick a size limit
Choose a preset such as 25 MB for Gmail or 20 MB for Outlook, or type any size you need.
- 3
Split
Each part is built and measured for real, then made as large as possible without going over.
- 4
Send the parts
Download all parts as a ZIP or one at a time, and attach them to separate emails.
Measured, not guessed
Every part is saved and weighed before it's accepted. Only a single page bigger than the limit can go over, and it's flagged.
Email-safe sizes
Optional headroom for email encoding, which makes attachments about a third bigger in transit.
No uploads
Your file is split on your own device — useful when the reason it's big is that it's full of scans of private documents.
Common email attachment limits
Gmail and Yahoo Mail accept attachments up to 25 MB, and Outlook can be as low as 20 MB. Company mail servers are often stricter, with 10 MB a frequent ceiling, and the recipient's server can have a lower limit than yours. Because many of those limits count the encoded message, leave the email encoding option on when the parts are going out as attachments.
How the parts are sized
The tool starts with an estimate based on the file's average page weight, builds that part and measures its real size, then grows or shrinks it — narrowing in on the largest number of pages that fits. Pages always stay in their original order, and no page is ever split across two files. Each part is filled as far as the limit allows, and its real size is checked before it's accepted.
Sending the parts
File names include the page range, such as report-pages-001-045.pdf, so the recipient can tell which part comes first. Number your emails too ("Part 1 of 3") in the subject line. If you'd rather send one link, a cloud drive is an alternative — but when attachments are required, splitting is the reliable option.
When to compress instead
Splitting keeps every page exactly as it is. If the file is only slightly over the limit, or a single page is huge (usually a high-resolution scan or photo), compressing first is the better move. Compress PDF reduces image size; you can then split the smaller file into fewer parts.
Pro tip: uploading to a web form rather than emailing? Turn off "Leave room for email encoding" — forms check the file size itself, so you can use the full limit.
Frequently Asked Questions
How do I split a PDF into parts smaller than 10 MB?
Upload the PDF, choose the 10 MB preset and switch off "Leave room for email encoding" if you want to use the full 10 MB. Click Split: every part is built and measured, and pages are grouped so each part is as large as possible while staying under the limit. File names include the page range, so the parts are easy to put back in order.
Why can a 24 MB PDF be too big for a 25 MB email limit?
Email attachments are encoded as text (Base64) on the way out, which makes them about 37% larger, and many mail systems count that encoded size. A 24 MB PDF is roughly 33 MB in transit, so it may be rejected or, in Gmail, turned into a Google Drive link. Keep "Leave room for email encoding" switched on and the parts are sized to fit after encoding — for a 25 MB limit that means parts of about 18 MB.
Why can't the tool just divide the file size by the number of pages?
Pages share resources. A font or logo used on every page is stored once in the original, but every part needs its own copy, and some pages carry large scans while others are nearly empty. That's why this tool measures each part's real size instead of estimating it.
What if a single page is bigger than the limit?
A page can't be split further, so it becomes a part on its own and is marked as over the limit. Compress the PDF first to shrink the images on that page, then split the compressed file.
Is it better to compress or to split a large PDF?
If the file is only a little over the limit, compressing usually solves it in one file, but it reduces image quality. Splitting keeps every page exactly as it was. For very large scans, compress first and then split if it's still too big.
Will the parts add up to the original size?
Usually slightly more, because shared fonts and images are repeated in each part that uses them. The results list shows the exact size of every part.