Upload limits are written in megabytes, but a PDF is divided in pages, and there is no reliable way to guess how many pages add up to ten megabytes. A chapter of plain text weighs almost nothing; a single scanned photograph can weigh more than fifty pages of text. This tool works the other way round from splitting by page count: you name the size each part must stay under, and pages are added to a part until one more would push it over the line.
How to use Split by Size
- Add the PDF you need to break up.
- Enter the maximum size for each part in megabytes. Set it a little below the real limit, so a mail system that adds encoding overhead still lets the message through.
- If the file is password protected, enter its password in the PDF password field.
- Select Split by Size.
- Download the ZIP. Each part is named after your document and labelled with the pages it holds, so they stay in order and you can tell at a glance what is in each one.
How a part is measured
The size that matters is the size of the finished file, not the sum of what the pages looked like inside the original, so each part is weighed as it is built.
- Weighed, not estimated: A candidate part is actually saved and measured before it is accepted. That is slower than counting pages, but it is the only way to promise that nothing comes out above the limit.
- Pages stay together and in order: Parts are cut from consecutive pages, so reading them one after another gives you the original document back. Nothing is reshuffled to pack the parts more tightly.
- Shared material counts once: A font or a logo used throughout the document is carried into each part that needs it, which is why two parts can hold very different page counts for the same size.
- Under, never over: A part is grown only while it still fits. The last page that would have tipped it over starts the next part instead.
Choosing a limit
The number to type is the one the system on the other end will accept, minus a margin.
- Leave headroom: Email attachments are encoded before sending, which adds roughly a third to their size. For a 25 MB mail limit, setting 18 MB here is a safer target than 25.
- Portals are usually literal: An upload form that says 10 MB normally means the file on disk, so 10 is a fair setting, though 9 costs nothing and avoids an argument with a rounding rule.
- Very small limits: You can go down to 0.05 MB. At that point most parts will hold a single page, and any page heavier than the limit is still delivered on its own rather than being dropped.
- Compressing instead: If the document only just exceeds a limit, shrinking it may be better than splitting it. Compress to Target Size aims at a size while keeping the file whole.
What you get back
- A ZIP of parts: Splitting produces several files, and one download is far more reliable than a burst of separate ones. Every current operating system opens a ZIP without extra software.
- Named by pages: Each part carries its position and its page range, like report-02-pages-13-28.pdf, so the order survives any file list and you can find a particular page without opening them all.
- One part means one PDF: If the whole document already fits under the limit there is nothing to split, so a single PDF is returned rather than a ZIP with one file in it.
- Putting it back together: Merge PDF joins the parts back into the original document if the recipient needs it whole once it has arrived.
When people use Split by Size
A court or tax portal with a hard cap
Filing systems often refuse anything over a fixed size and give no useful error. Splitting to just under the cap gets every page accepted in consecutive uploads.
Emailing a scanned bundle
A scanned contract with photographs attached can run to tens of megabytes. Parts sized for the mail limit go out as a short series of messages instead of bouncing.
Slow or metered connections
Smaller parts fail less often and resume faster, which matters when the upload is over a phone connection or a site link that drops.
Limitations to know
A single page larger than the limit cannot be made to fit, so it is delivered on its own and that part will exceed the size you set. Compress the file first if that happens. Because each part is saved and measured, a very large document with a very small limit takes noticeably longer than a plain page-range split. Bookmarks, form fields and attachments are not carried into the parts.
Split by Size: common questions
Will every part really be under the size I set?
Yes, with one exception: a single page that is already bigger than the limit. Parts are built by adding pages and weighing the result, and a page that would push a part over the line starts the next part instead. Only a page that cannot fit anywhere is delivered oversized, on its own.
Why do the parts have different numbers of pages?
Because pages weigh different amounts. A page of text is a few kilobytes; a page holding a scanned photograph can be several megabytes. The tool fills each part up to the size you asked for, so a stretch of plain text produces a part with many pages and a run of scans produces one with few.
Should I split or compress?
Compress first if the file is only somewhat over the limit, since one file is easier for everyone. Split when the document is far too large, when compressing would cost too much quality, or when the recipient has a hard per-file cap that no amount of compression will meet.
What size should I enter for email?
Somewhat below the stated limit. Attachments are encoded before being sent, which inflates them by around a third, so a 25 MB mailbox realistically accepts a file of about 18 MB. Entering 18 rather than 25 avoids messages that bounce after they appear to have sent.
Can I get the original document back?
Yes. The parts are consecutive and named with their page ranges, so Merge PDF joins them back in order into a file identical in content to what you started with.