Why is my PDF so big?
Almost every oversized PDF is large because of images: scanned pages, phone photos of documents, or high-resolution pictures pasted into a report. A single scanned page saved at 600 DPI in colour can be 5 MB on its own. Text and lines take very little space. That is why compression works best on scans and photo-heavy files, and why a 40-page typed contract may already be as small as it can be.
Which compression level should I choose?
- Recommended (144 DPI): the best balance for email attachments, job applications, visa and university portals. Text in scans stays clearly readable.
- Strong (100 DPI): the smallest file. Use it when a form has a strict limit such as 1 MB or 500 KB.
- Light (200 DPI): sharper pages for printing, with a smaller saving.
- Lossless: tidies the file structure without touching any image, so text stays selectable and links and form fields keep working. Savings are usually small.
For scanned black-and-white documents, also tick Black and white: colour information is dropped and the file shrinks further.
How the compression works
Recommended, Strong and Light redraw each page at the chosen resolution and save it as a compressed JPEG image inside a new PDF. This is the same method many paid tools use for their strongest setting. It is very effective, but the pages become images: you cannot select or search the text afterwards, and links and form fields are removed. If you need the text, extract it first with PDF to Text, or choose Lossless.
Everything happens in your browser. Your PDF is never uploaded, so it is safe for bank statements, payslips, medical letters and ID documents.
Still too big? Three more ways to shrink a PDF
- Remove pages you do not need, such as blank backs of scanned sheets, with Delete PDF pages or Remove blank pages.
- Split a long document into parts with Split PDF into files and send them separately.
- If you are making the PDF from photos, shrink the photos first with Compress image, then use JPG to PDF.