How to make a PDF smaller for email or upload

Most email providers cap attachments around 20–25 MB, and plenty of upload forms are stricter than that. If a PDF is over the limit, compressing it is usually the fastest fix — faster than re-exporting from the original source file, if you even still have it.

Tool King's Compress PDF tool works by stripping unused metadata and optimizing the internal structure of the file (using what's called object streams), which reduces size without touching the visible text or images. Upload your PDF, click Compress, and download the smaller version.

It's worth setting expectations correctly: this kind of compression is lossless and safe, but it isn't magic. A PDF that's mostly text with light formatting might shrink noticeably, since a lot of that size comes from redundant metadata and structural overhead. A PDF full of high-resolution scanned images won't shrink nearly as much, because the images themselves aren't being re-encoded — doing that safely requires a more heavyweight tool and usually trades away some image quality.

If you regularly work with scanned documents and need much smaller files, scanning at a lower resolution in the first place will do more than compressing after the fact.