How to Split a PDF by File Size (Under 10 MB)

PixelTools splits a PDF by page, not by megabytes, so you pick the page ranges and then check each part's size. Work out roughly how many pages fit under your limit, split with Split PDF, and look at the file sizes. If one part is still too big, split that part again or run it through Compress PDF. Some desktop tools, Adobe Acrobat Pro among them, have a Max MB field that does the arithmetic for you, but the result is the same kind of page-range split. Everything in our tool runs in your browser, so a confidential file never gets uploaded.

Dividing the file size by the page count gives a rough number, and it is often wrong. We built a 12-page test PDF where pages 1 to 3 each hold a large photo and pages 4 to 12 are plain text. The whole file was about 4.2 MB. Splitting it into 4-page chunks gave one part of 4.2 MB (it held all three photo pages) and two parts of about 0.6 MB each. Equal page counts produced wildly unequal files. A scanned document behaves the same way when a few pages are dense colour scans and the rest are near blank.

This surprised us: in the same test, splitting into single photo pages plus one text block gave parts of 1.8 MB, 1.8 MB, 1.8 MB and 0.6 MB, a total of about 6.0 MB against the 4.2 MB original. The cause is a letterhead image that sits on every page. In the original file it is stored once and every page points to it. Each split part has to carry its own copy, so splitting into four parts stores it four times. Documents with a shared logo, background or font pay this cost for every extra part, so fewer, larger parts is the cheaper route.

Start by checking the original size and your target, say 10 MB. Open Split PDF and make a first guess, such as splitting in the middle if the file is 18 MB. Download the parts and read their sizes in your file manager. Any part still over the limit goes back into Split PDF for a second cut, ideally at a natural break such as a chapter start. If a single page is the problem, one photo page can exceed several MB on its own, and no split will shrink it. Compress that part instead, or compress the whole file first, then split.

Compress first if the file is only a little over the limit, because one 11 MB file that becomes 8 MB beats two split files the recipient has to open separately. Split first if the receiving system caps the size per upload and you need every page at full quality, such as a court filing portal or a tender submission. In that case also check whether the portal wants parts named in order. Our split tool names parts by page range, for example pages-1-40, which keeps the order obvious in a folder.

Open each part and confirm the first and last page match your plan, because an off-by-one range is the usual mistake. Check that the sizes are really under the limit with some margin, as email systems add overhead to an attachment and a 9.9 MB file can be rejected under a 10 MB cap. Bookmarks and internal links that point to pages in another part will not work any more, since each part is a standalone document. If you need those, split at section boundaries so each part's links stay inside it.