How to reduce PDF file size
November 3, 2026 2 min read
Even a few pages scanned with your phone can be too big for an email attachment or the upload limit of a government, school or job application portal. The problem is rarely the number of pages. It's the high resolution photos inside them.
Compress PDFShrink image-heavy PDFs.Why is the PDF so big?
What really decides a PDF's size is the images inside it. A phone camera captures each page at a very high resolution, far more than you need to read it on screen or print it. A PDF that contains only text is usually small already.
How to shrink the PDF
The Compress PDF tool saves the pages again at a lower resolution to make the file smaller. The document stays readable while unnecessary detail is dropped. The size limit of the site you're uploading to is usually shown next to the upload field, so compare the result with it.
- 1Open the Compress PDF tool and pick your file.
- 2Choose a compression level: Light, Balanced or Strong. Balanced is enough for most documents.
- 3Press Shrink, check the new size and download the file.
- 4If it's still over the limit, try Strong on the original file.
The one thing to know: text stops being selectable
This tool works by turning pages into images. That means you can't select, copy or search the text in the compressed PDF. With scanned documents the text is already an image, so you won't notice. With a PDF made on a computer you may need the text later, so keep the original file.
PDFs that are mostly text barely shrink this way. When that happens, the tool tells you.
Other ways that help
Removing pages you don't need also cuts the size: with Split PDF and extract pages you can save just the pages that were asked for as a new PDF. If you're building the document from photos, choosing A4 in the Image to PDF tool scales very large photos down to a resolution that is plenty for printing, so the file starts out smaller.
Everything runs in your browser. IDs, certificates or medical documents are never uploaded to a server.