Why are PDF files sometimes so large?
Most of a PDF's size usually comes from images. A document scanned at high resolution, a presentation full of photos or a PDF made from phone pictures can easily grow to tens of megabytes. That becomes a problem when you email it (Gmail and most providers limit attachments to 20–25 MB), upload it to a government or university portal, or send it through a messaging app.
Compress PDF lowers the resolution of images and recompresses them, removes duplicates and optimizes fonts, while text stays sharp and searchable. Scanned documents and photo-heavy PDFs often shrink by 50–90%.
Compress several files at once
You can select several PDF files at once (or add more with the "Add more" button). They are all compressed with the same level, one after another, and you download them together in a single ZIP archive – handy when you send a complete set of documents, such as all attachments for an application.
Which level should I choose?
| Level | Image resolution | When to use it |
|---|---|---|
| Strong | 72 dpi | When the file must be as small as possible and will only be read on screen. |
| Recommended | 150 dpi | For email, portals and archiving – a good balance of quality and size. |
| Light | 300 dpi | When the document also needs to print in good quality. |
If a file is already optimized (for example a PDF exported from Word without images), compression cannot shrink it much. In that case we return your original file, so you never end up with a bigger document.
What happens to your files
Image compression requires server-side processing, so files are sent over an encrypted HTTPS connection. They stay on the server only while being processed – usually a few seconds – and are deleted automatically as soon as the result is returned. We make no copies and never read or reuse your documents. The maximum size is 95 MB per file.