Some documents are simply too large to compress their way under an attachment limit — a 300-page manual, a photo-heavy report, a scanned archive. When that is the case, the practical fallback is not to keep compressing at the cost of quality, but to divide the document into a handful of roughly equal parts and send them across separate emails.
Split PDF handles the actual splitting; the planning is mostly about deciding where to cut.
Working out how many parts you need
- Check the document's total size and your attachment limit (commonly 10–25 MB, see your mail provider's specific figure).
- Divide the total size by the limit, then round up, to get a rough minimum number of parts — a 60 MB file with a 10 MB limit needs at least 6 parts.
- Add a small margin: aim for parts noticeably under the limit rather than right at it, since size does not always split perfectly evenly by page count.
Steps
- Open the document and note its total page count.
- Divide the pages into roughly equal ranges matching the number of parts you calculated — for a 300-page document split into 6 parts, that is pages 1–50, 51–100, and so on.
- Upload the file to Split PDF and extract each range as its own PDF.
- Check the size of each resulting part against your limit before sending.
Why page count alone is not always a perfect proxy for size
A document with images concentrated in certain sections will not split evenly by size just because the page ranges are even. If your document has, say, a heavily illustrated middle section, that part may come out considerably larger than the others even with the same page count. After splitting, check each part's actual file size, and if one part is unexpectedly large, either split it further or run it through the PDF Compressor on its own.
Naming and numbering the parts clearly
Once you have several files, clear naming matters more than it might seem — “Report-Part-1-of-6.pdf” through “Report-Part-6-of-6.pdf” tells the recipient immediately how many emails to expect and in what order to read them. A vague name like “report2.pdf” leaves them guessing whether they have received everything.
Telling the recipient what to expect
It helps to send a short note, either in the first email or as a separate message, explaining that the document is arriving in several parts and how many there are in total. Without that context, a recipient who only receives part 3 of 6 (because an earlier email bounced, for instance) may not realise anything is missing.
When compressing is still worth trying first
Splitting is the reliable fallback, but it is still worth a quick compression pass first — if the PDF Compressor gets the whole document under the limit in one go, that is simpler for everyone than managing several emails. Reach for splitting when compression alone genuinely cannot get there without unacceptable quality loss, or when the document needs to stay at full quality for another reason.
Reassembling the parts later
If the recipient (or you, later) needs the document back as one file, Merge PDF combines the parts back together in the correct order — as long as they are added in sequence, the reassembled file is identical to the original.
Frequently asked questions
Is there a better way than splitting for a genuinely huge file?
A cloud storage link is the other common option, though it depends on the recipient being able and willing to use one. Splitting keeps everything as normal attachments, which is more universally reliable.
Does splitting affect the quality of the content?
No, each part keeps its pages exactly as they were in the original — splitting does not compress or alter anything, it only divides the document.
How many parts is too many?
There is no hard rule, but beyond 5–6 parts it is often worth reconsidering whether a shared link would genuinely be easier for both sides.
Can I split unevenly, by section rather than equal page count?
Yes — splitting by logical section (chapters, for instance) rather than strictly equal page counts is often more useful for the reader, even if the resulting file sizes vary more.
Is it free?
Yes. No sign-up, no watermark, and files are removed from the server automatically about an hour after processing.