Upload forms that stop at 2 or 5 MB, and email attachments that bounce above 20 to 25 MB, turn a heavy PDF into a real obstacle. This compressor offers two approaches with very different trade-offs, so you can pick the one that suits the document instead of hoping a single slider does the right thing.
Both run inside your browser. Light re-saves the PDF in a more compact structure without touching its content. Strong redraws every page as a JPEG image at the resolution you set, which can cut scanned and photo-heavy files dramatically but turns text into pictures. In either mode the result is never larger than the file you started with: if compression does not help, you get your original back.
Light and Strong compression explained
Light compression re-saves the document using object streams, a PDF feature that packs the file's internal structure more tightly. Text, fonts, images and links are left exactly as they were, so the result is lossless. How much it saves depends on how the file was made: PDFs from older software or ones edited many times may shrink noticeably, while files already saved efficiently by modern tools often barely change.
Strong compression takes a different route. Each page is rendered at the Image resolution (DPI) you choose, from 50 to 300 with 110 as the default, encoded as a JPEG and placed on a new page of the same size. Oversized embedded photos and scans are replaced with one right-sized image per page, which is where the big savings come from. The price is that each page becomes a picture: text can no longer be selected, searched or copied, links stop working, and a warning says so whenever Strong is selected.
Which level to pick
Text documents and anything you need to search
Contracts, reports and e-books exported from Word or a browser should use Light. Their weight usually comes from fonts and structure, and keeping the text selectable matters more than a few hundred kilobytes.
Scans and phone photos saved as PDF
A scanned document is already a stack of images, often stored at 300 DPI or more. Strong at 100 to 150 DPI typically shrinks such files a lot while staying readable on screen, and nothing that was selectable is lost, because a scan had no text layer to begin with.
Meeting a hard upload limit
When a portal refuses anything above a fixed size, start with Strong at the default 110 DPI, check the result and lower the DPI step by step if it is still too big. Somewhere below 75 DPI small print starts to blur.
Choosing a DPI
DPI sets how many pixels each inch of the page receives. Around 72 is enough for a quick look on screen, 110 keeps ordinary body text legible with a little zoom, 150 is comfortable for documents that may be printed, and 200 to 300 approaches scan quality but saves much less. JPEG quality is fixed at 70 percent, so DPI is the one control that trades size against clarity.
Pages keep their original dimensions in Strong mode, so a printed page comes out the same size as before. Very large pages are rendered at a lower resolution if the requested DPI would exceed the browser's canvas limit. Each result shows the percentage saved compared with the original file.
Comment utiliser cet outil
- Drop one or more PDFs on the box above, or click Choose files (up to 200 MB each).
- Under Compression, choose Light for a lossless re-save or Strong for maximum reduction.
- With Strong, set Image resolution (DPI); 110 is a good starting point.
- Press Convert and compare the size and saving shown for each file.
- Download the compressed copy, which has -compressed added to its original name.
Trade-offs and limits
- Strong mode makes text unselectable and unsearchable and removes links and form fields, so it does not suit documents someone needs to edit or copy from.
- Strong mode replaces charts and drawings with pixels, so they lose their crispness when zoomed far in.
- Light mode only reorganises the file. A PDF that is large because of big photos will hardly shrink without Strong.
- Password-protected PDFs are not supported and show an error. A PDF that opens freely but is locked against changes by its owner works in Strong mode only, because Light has to edit the file.
- If Strong mode cannot draw part of a page, such as an image in a format the in-browser renderer cannot decode, it stops with an error instead of returning a page with that content missing.
- If compression would not make the file smaller, the original is returned unchanged rather than a larger copy.