Split a PDF into parts that fit a size limit
Email services refuse large attachments, and upload forms often stop at 10 MB, 5 MB or 2 MB per file. When a scanned book, a long contract or a project report is bigger than that, the Split PDF by Size tool divides it into as few parts as possible, each one under the limit you choose.
It does not guess from page counts. Each candidate part is built and saved exactly as it will be downloaded, so its real size is known, and pages are added to a part for as long as it still fits. Parts are named with their number and page range, and you can download them one by one or together as a ZIP.
All of this happens on your own device — the PDF is never uploaded, which matters for confidential reports, medical files and legal documents.
How to split a PDF by file size
- Drop your PDF onto the upload area or click to choose it. Its page count and size appear at the top.
- Choose the maximum size of each part: 20 MB, 10 MB for email, 5 MB, 2 MB, 1 MB, or “Custom” for any size in KB or MB.
- Read the note below the options — it estimates how many parts to expect.
- Press “Split into parts under …” and wait while each part is measured.
- Download a single part with its download button, or everything with “Download all (ZIP)”.
Split PDF by Size features
Exact sizes, not estimates
Every part is saved and measured while it is being filled, so the size you see is the size of the file you download.
As few parts as possible
Pages are packed greedily in order: each part takes as many pages as fit before the next one starts.
Pages stay in order and untouched
Pages are copied, not re-rendered, so text stays selectable and images keep their quality.
Oversized pages handled
A single page bigger than the limit is flagged and can be compressed on its own to fit, leaving every other page as it was.
Clear file names
Parts are called, for example, report_part-2_pages-38-74.pdf, so the order and contents are obvious.
Links kept within parts
Links that jump to another page keep working when the target page is in the same part.
Choosing the right part size
For email, 10 MB parts are a safe choice. Many mail services cap a message at 20–25 MB, and attachments grow by roughly a third when they are encoded for sending, so a 10 MB file uses about 13–14 MB of that allowance. Send one part per email if your provider is strict.
For upload forms, use the limit printed next to the upload box. If the form says 2 MB per file, choose 2 MB. Sizes here are decimal — 1 MB is 1,000,000 bytes — so a part under 2 MB also passes a check that counts 1 MB as 1,048,576 bytes.
| Where the file goes | Suggested part size |
|---|---|
| Email attachment | 10 MB (5 MB for older or company mailboxes) |
| Messaging apps and cloud forms | The limit shown in the app |
| Government and job portals | Usually 1–5 MB per file — check the instructions |
| Printing services and archives | 20 MB or larger |
Why parts can add up to more than the original
A PDF stores fonts and shared images once and lets every page use them. When the document is divided, each part needs its own copy of the fonts and images its pages use, so the parts together are often a little larger than the original. That is also why the tool measures real files instead of dividing the size by the page count.
If one page is enormous — a high-resolution photo or a scanned map — no split can make it smaller. The tool puts it in a part of its own and offers to compress just that page into an image that fits. To shrink the whole document instead, use Compress PDF to a Target Size or Compress PDF.
Related ways to divide a PDF
- Split PDF divides by page ranges, every page, or every N pages when you know which pages go where.
- Extract PDF Pages pulls out selected pages into one new file.
- Merge PDF puts the parts back together later in the right order.
Split PDF by Size FAQ
How do I split a PDF into 10 MB parts?
Add the PDF, keep “10 MB · email” selected and press “Split into parts under 10 MB”. The tool fills each part with as many pages as fit under 10 MB and gives you the parts as a ZIP or one by one.
Why is one of my parts over the limit?
That part contains a single page that is bigger than the limit by itself — usually a large photo or scan. Press “Compress oversized pages to fit” to turn just that page into a smaller image, or pick a larger limit.
Does splitting by size reduce quality?
No. Pages are copied exactly, so text, images and vector graphics are identical to the original. Only pages you choose to compress after an oversize warning are changed.
Can I split a PDF by size for Gmail or Outlook?
Yes. Choose 10 MB — attachments grow by about a third when sent, and 10 MB parts stay comfortably within typical 20–25 MB mail limits. Attach one or two parts per email.
Is it safe to split confidential PDFs here?
Yes. The file is processed in your browser and never uploaded, so nobody else can see it.
Are bookmarks kept in the parts?
Bookmarks belong to the whole document, so they are not copied into the parts. Page content, comments and links between pages in the same part are kept.