Free · Private · In your browser

Split PDF by Size

Split a PDF into multiple parts each under your target file size (MB).

Drop your files here, or click to browse
Processed on your device — nothing is uploaded

How your files are handled

We built these tools so you never have to wonder where your documents go. Here is exactly what happens when you use them.

  • Your files are processed entirely in your browser using open-source libraries (pdf-lib, PDF.js, and others).
  • Nothing is uploaded to our servers. We have no backend that receives, stores, or scans your documents.
  • We cannot see, store, or access your files — not during processing, not after, not ever.
  • Processing uses your device's memory and CPU. Large files may take longer, especially on phones and tablets.
  • All tools are free with no paywall tricks, no hourly task limits, and no watermarks on your output files.

How it works

Three simple steps. Your files never leave your device, and the result downloads straight to your computer or phone.

Frequently asked questions

Common questions about privacy, pricing, and how these tools work.

More organize tools

Other free PDF utilities that work the same way — private, in-browser, no sign-up.

How to split by Size

Split by Size breaks a large PDF into smaller parts, each kept under a size limit you set in megabytes. It is useful when an email or upload form rejects files above a certain size.

  1. Add your PDF; it opens in your browser and stays on your device the whole time.
  2. Enter the maximum size in MB that you want each part to stay under.
  3. Click Split by size to pack pages into parts one at a time until each nears the limit.
  4. Download a ZIP containing the numbered parts.

Everything happens in your browser — your file is never uploaded, and there is no sign-up, watermark, or limit.

Frequently asked questions

Are my files uploaded to a server?

No. Every tool runs entirely in your browser using open-source libraries, so your file is processed on your own device and is never uploaded. We have no backend that receives, stores, or scans your documents.

Is it really free, and will there be a watermark?

Yes. There is no account, no sign-up, and no hourly limit, and the tools never add a watermark to your output. UnboundPDF is free and is not affiliated with Adobe.

Does it work on a phone or tablet?

Yes. The tools run in any modern mobile browser as well as on desktop. Because the work uses your device's own memory and processor, very large files simply take longer on phones.

What if a single page is larger than my limit?

Each part always contains at least one page, so a page bigger than the limit becomes its own part, and the tool tells you when that happens.

Are pages ever cut in half to hit the size?

No. Splitting happens only at page boundaries, so pages are never divided; parts are built by adding whole pages until the limit is reached.