Split by size
What Split by size actually does
Splitting a document by page count and hoping the parts are small enough does not work, because pages are not the same size: ten pages of a scanned photograph can outweigh two hundred pages of type. This page splits by the thing that actually matters, measuring each part as it is built and starting a new one before the target is passed. The target is worth thinking about rather than setting to whatever cap you were quoted. Mail does not send an attachment as raw bytes; it encodes it into text first, and the standard that defines that encoding states the encoded data is consistently about thirty-three percent larger than the original. A file sitting just under an advertised cap is therefore over it by the time it arrives, which is the usual explanation for an attachment that was refused at what looked like a safe size. Setting the target to roughly three quarters of the cap absorbs that. Measuring honestly costs something: the document is rebuilt once per page to find each real boundary, so the page count this accepts is capped, and a very long document belongs in the page ranges tool where you choose the boundaries yourself.
How to use it
- Choose the PDF.
- Set the target in megabytes, allowing for the growth if the parts are going by mail.
- Run it. Each part is built and measured, and a new part starts before the target would be passed.
- Check the reported size of every part before downloading, since a single page larger than the target has to go somewhere.
- Download the parts. They are consecutive and cover the whole document in order.
Useful for
- Send a long scanned document through a mail service that refuses large attachments.
- Prepare parts for an upload form or filing system with a per-file cap.
- Break a large deposit into pieces small enough to survive a slow or unreliable connection.
- Split a document for a system that caps size rather than page count.
Limits worth knowing
- The document is rebuilt once per page to measure honestly, so the page count is capped here. A longer document belongs in the page ranges tool.
- A document under two pages cannot be split and is refused with the reason.
- A single page larger than the target still becomes a part on its own and exceeds it. Pages are the smallest unit; making one smaller is a compression job.
- Parts are consecutive page ranges. Reordering, or grouping by chapter or bookmark, is not offered here.
Questions people ask
What target should I set for email?
Below the cap rather than at it. An attachment is encoded for transit and grows by about a third, so roughly three quarters of the advertised cap is the safe figure.
Why can it not split a very long document?
Because it measures each boundary by actually building the part rather than estimating it. That is accurate and it is slow, so the page count is capped. Use the page ranges tool for long documents.
One part is bigger than my target. Why?
A single page exceeded the target on its own. A page cannot be divided, so it becomes a part by itself. Compressing that page first is the fix.
Are the parts in order?
Yes. They are consecutive ranges and together they cover the whole document.