Split a PDF under a maximum size
The site takes 10 MB at most and your PDF is 34. Here you choose how much each piece may weigh and the document is cut into parts that all stay under that limit, with the pages untouched. The file stays on your device.
Why it is not «four equal parts»
Because pages do not weigh the same. In a scanned document a page with a photo can weigh a hundred times a page of plain text, so «34 MB divided by 10 makes four parts of nine pages» produces pieces that bust the limit anyway, and you find out only when the portal refuses them. The one honest way to know what a part weighs is to build it and weigh it: here every piece is really created and measured before you get it, and the cutting point is found by halving the guess each time, so a three-hundred-page document takes about ten tries instead of three hundred.
The limit: 1 MB here means one million bytes
Bytes can be counted two ways and the difference is 5%: 1 MB = 1,000,000 bytes (the way websites, mailboxes and the Mac count them) or 1,048,576 (mebibytes, the way Windows counts them). The first one is used here because it is the stricter: if the portal meant the other one, your parts still stay under. And there is something almost nobody knows: an email attachment is rewritten in a form that makes it grow by about a third, so with a mailbox that accepts 25 MB the real file has to stay under 18-19 MB. If you are preparing an email, aim there.
The pages stay exactly as they were
Pages are not recompressed nor turned into photographs: what goes into the parts are the original pages, with the same text you can select and search and images at their starting quality. What does not travel into the parts are the bookmarks (the side index) and internal references pointing to a page that ended up in another piece: that is unavoidable, because in that file the page is no longer there. And as with any tool that rewrites a PDF, a digital signature does not stay valid: if the document is signed, it has to be sent whole.
When a single page busts the limit
It happens with scans made at 600 dpi in colour: one page alone can weigh 15 MB. Splitting is useless then, and this page says so plainly instead of spinning: that page has to get lighter, which is the job of Compress a PDF. The route that nearly always works is: compress first, then split what is left.
The other ways to cut a PDF
If you already know which pages you need (the first ten, the chapter in the middle) the cut is made by page number with Split a PDF. If instead you have to put the pieces back together, there is Merge PDFs: whoever receives the parts can rebuild the document with that same page, and it is worth telling them. If the PDF asks for a password when it opens it cannot even be read: the password has to come off first, with Remove the password from a PDF.