Compress PDF
Reduce a PDF's file size — losslessly, or by rebuilding scanned pages as images when you need much bigger savings.
What it does
Compress PDF makes the file smaller by re-encoding what is inside it, not by zipping it up. You choose how hard to push, and the size you end up with depends far more on what the file contains — photographs, scans, flat graphics — than on how long it is.
When you need it
Almost always an upload limit: a mail server that bounces anything over 10 MB, a portal that refuses the attachment, a form that silently fails, or a page that loads slowly because its images were never resized.
Limits and caveats
Compression is lossy at the stronger settings, and quality that has been thrown away cannot be recovered from the output — keep your original. A file that is already compressed will barely shrink, and that is the format working correctly, not the tool failing. Everything happens in your browser, so the file never leaves your device.
How to compress pdf
- Drop the PDF that's too big to send.
- Pick lossless (keeps text selectable) or rasterise (much smaller, text becomes image).
- See the real before-and-after size before you download.
Frequently asked questions
- Why did lossless compression barely help?
- Because the PDF was mostly text, which is already compact. The bulk in large PDFs is nearly always embedded images — that's what rasterising targets.
- What does rasterising actually cost me?
- The text stops being selectable, searchable and screen-reader accessible, because each page becomes a picture. For scans that's no loss — they were images already.
- What if the result is bigger than the original?
- KIVO tells you and keeps your original rather than handing back a worse file.