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You want a smaller file, but the document has to look just as good. That’s possible, as long as you know what compressing actually does: it only shrinks the images in your PDF, such as photos and scans. Text is never touched.
What makes a PDF large?
A PDF consists of text, drawings (lines, shapes, charts) and images. Text and drawings take up very little space and stay sharp at any zoom level. Images are almost always what makes a file large: a single phone photo can weigh several MB, and a scanned page is in fact a photo too. That is where compressing gains space.
How it works
- Open Compress PDF and choose your file.
- Choose Light. That level gives the best quality, with the smallest saving.
- Click Compress and download the result.
- Check the file. Still too big? Try Balanced and compare again.
What each strength does
- Light keeps every image at its original resolution and only stores photos more efficiently. Images that were stored without loss stay that way.
- Balanced also reduces images to about 200 dpi. On a screen and on paper that is still sharp, and the saving is often large.
- Strong reduces images to about 144 dpi. That gives the smallest file, but photos look softer when you zoom in.
What stays the same?
- Text stays sharp, selectable and searchable.
- Links, bookmarks and form fields keep working.
- Only photos and scans are stored smaller.
How to check the quality
- Open the original and the compressed file side by side.
- Zoom in to 100 to 200 percent on a page with a photo or small print.
- Will the document be printed? Print one page as a test.
See no difference? Then you can safely use the smaller file.
To be honest
Recompressing photos without any loss at all doesn’t exist. “Without losing quality” here means: without visible loss. With Light you usually won’t see a difference on screen. With Strong the file gets smallest, but then you will see the loss.
Compressing an already compressed file again adds a little loss each time. Keep the original, and if the result is not small enough, compress the original again at a stronger level.
When compressing barely helps
- Mostly text: there is little to shrink. If the file doesn’t get smaller, you simply get your original back.
- Already optimized: PDFs that were exported for the web are often already compact.
- Many pages: then leaving out pages or splitting the file helps more.
You can also shrink the JPG photos in Word and PowerPoint files this way; the text stays editable.
Frequently asked questions
Which strength should I choose for printing?
Light or Balanced. At about 200 dpi, photos still print sharply on a normal printer. Strong is fine for reading on a screen.
Can I undo the compression?
No, the removed detail can’t be restored. That’s why your original stays untouched: you always download a new file.
Is my PDF uploaded when I compress it?
No. Compressing happens in your own browser, on your own device.