How to use it
Most of a PDF's weight is the pictures inside it, so there are two honest ways to shrink one in a browser. The default mode keeps the document intact: it finds the embedded pictures, re-encodes JPEG and plain colour or grey images at a lower quality and, if they are very large, a lower resolution, and replaces a picture only when the new version is clearly smaller. Text, fonts, links and vector drawings are not touched. The result lists how many pictures were found, re-compressed and left alone.
The maximum mode is a stronger method for scanned documents and photo PDFs: each page is redrawn as a picture at a resolution of 60 to 150 DPI and the PDF is rebuilt from those pictures. It can shrink a file dramatically, but the text is no longer selectable or searchable, links stop working, and for a text-only PDF the result can even be bigger, in which case the tool tells you the compression did not help and offers no download. You can set a target size in KB, and it will step through stronger settings until the file fits.
Results vary from file to file, and a PDF that is already optimised or contains no pictures may not shrink at all; the tool never presents a larger file as a success. Compression changes the file, so digital signatures become invalid, and you should keep the original. Everything is done in your browser with no upload. To take pages out first use Split PDF, to combine files use Merge PDF, to build a PDF from photos use JPG to PDF Converter, and to prepare pictures beforehand use the Image Compressor.
Supported formats and limits
| Input | One PDF at a time, up to 150 MB. Password-protected files can be opened with their password; the output is not protected. |
|---|---|
| Keep text mode | Re-compresses embedded JPEG images and plain RGB or grey images; text, fonts, links and vector graphics are untouched. Only images that become clearly smaller are replaced. |
| Maximum mode | Redraws each page as a picture (60–150 DPI) and rebuilds the PDF. Text stops being selectable and links stop working. |
| Target size | Optional KB target: the tool tries stronger and stronger settings until the file fits, and says if it cannot. |
| Not compressed | CMYK, indexed or masked images, and PDFs with no pictures. Text-only PDFs usually cannot be made much smaller. |
| Limits | Results vary a lot between PDFs. Digital signatures are invalidated; the original is never changed. |
Practical examples
A scan or photo-heavy PDF
- Situation
- A PDF made from phone photos, compressed in “keep text” mode at Medium.
- What to expect
- These files are mostly pictures, so savings can be large. The result shows original and new size and the number of pictures re-compressed.
A text-only PDF
- Situation
- A report with mostly text and a few vector charts.
- What to expect
- The tool says it could not make the file smaller. That is honest: there are no big pictures to shrink, and redrawing pages as pictures usually makes such a file larger.
A form that limits uploads to 200 KB
- Situation
- Enter 200 as the target size in Maximum mode.
- What to expect
- The tool tries progressively lower resolutions and qualities until the file is under 200 KB, or tells you it could not get there.
The numbers behind it
saving (%) = (original size − compressed size) ÷ original size × 100picture pixels are limited so that the longest side ≤ the level's limit (800–2400 px) at 35–85% JPEG quality
- “Keep text” mode changes only the pictures inside the PDF
- “Maximum” mode redraws every page at 60–150 DPI and stores it as a JPEG picture
Most of a PDF's weight is usually its pictures, so shrinking them shrinks the file.
Honest limits
- Results vary widely; text-only or already optimised PDFs may not shrink.
- Maximum mode turns pages into pictures: text is no longer selectable and links stop working.
- Digital signatures become invalid after compression.
- Files above 150 MB are not accepted.