Sejda PDF

Split PDF by size

Produce smaller parts that fit an upload limit.

Drag & drop your files here

Supported: PDF

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About Split PDF by size

Set a maximum size - 10 MB for an email attachment, for example - and the document is cut at page boundaries so that no part exceeds it.

  • Respects mail attachment limits
  • Never splits inside a page
  • Reports the size of each part

How to split pdf by size

  1. 1

    Upload the PDF

    Any size document works.

  2. 2

    Set the size cap

    Enter the maximum megabytes per part.

  3. 3

    Get the parts

    Splits always land between pages, never mid-page.

A practical guide to split pdf by size

Splitting to beat an upload limit

The main reason to split by size is a hard cap somewhere downstream: an email attachment ceiling, a portal that rejects anything over a set number of megabytes, or a form with a strict file limit. Enter the cap, and the document is carved at page boundaries so every part slips under it. Because email re-encodes attachments and inflates them slightly, set your limit a touch below the true ceiling rather than exactly at it. That small buffer is the difference between a part that sends cleanly and one that bounces back for being a hair too big.

Compress first, split second

Splitting by size treats the document as fixed and works around its weight, but often the smarter move is to reduce that weight first. A scan-heavy PDF that would break into six parts might fit in two, or even one, after compression resamples its images. So when a file is large because of photos or scans rather than sheer page count, run compress before splitting and re-check whether you still need to split at all. Keep the split for cases where the content genuinely cannot shrink further, such as a long document that is already lean per page but simply has many pages.

When a single page is bigger than the cap

Occasionally one page, usually a high-resolution scan or a detailed diagram, is larger on its own than the size limit you set. That page cannot be shrunk by splitting, so it becomes its own part and is flagged in the summary rather than silently breaking the limit. When you see that flag, the fix is to compress that page's images or, if it is a scan, lower its resolution before splitting again. Checking the per-part size report after every split is a good habit, because it tells you immediately whether the whole document actually cleared the cap or whether one heavy page needs separate attention.

Frequently asked questions

How does the tool decide where to cut?
It adds pages to a part until the next page would push it over your chosen limit, then starts a new part. Cuts always land between whole pages, never inside one, so no page is ever torn across two files. Each part comes back numbered in order with its size shown.
What size limit should I set for email?
Set it a little below your mail provider's attachment cap to leave room for the encoding overhead that email adds, so a ten-megabyte limit is a safe target for a service that allows around twenty-five. If parts are still awkward to send, compressing the document first often removes the need to split at all.
Why did I get more parts than I expected?
Image-heavy or scanned pages are large, so a document can hit the size cap after only a few pages, producing many parts. Running the compress tool before splitting shrinks those pages and usually yields fewer, fuller parts. The summary lists each part's size so you can see where the weight sits.
Does splitting by size reduce the total file size?
No. It divides the document into smaller pieces, but the pages themselves are copied across unchanged, so the parts add up to roughly the original size. To actually make the content lighter, use the compress tool, which resamples images while keeping text sharp.

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