About Compress PDF
Most of a PDF’s size usually comes from the images inside it. Stronger levels re-compress and downsample those images; the light level keeps them close to the original and only cleans up the file structure.
If a PDF is already well optimised and cannot get smaller, you get the original back and the page tells you so, rather than a larger file.
Which level to use
| Level | Images inside the PDF | Use when |
|---|---|---|
| Light | Up to 300 dpi | The PDF will be printed |
| Balanced | Up to 150 dpi | Email, sharing, most uploads |
| Strong | Up to 72 dpi | Strict size limits, on-screen reading only |
Getting a PDF under an upload limit
Scanned documents and PDFs full of photos shrink the most, because their size comes from images. Text-only PDFs are already small and change little.
- Start with Balanced and check the size shown before downloading.
- If it is still over the limit, try Strong.
- Still too large? Split the PDF into parts and compress each one.
What is not changed
Text, fonts and vector drawings are kept, so text stays sharp and searchable. If a file cannot be made smaller, GlobTool returns the original rather than a larger file.
How to use it
- 1Choose or drop a PDF
- 2Pick Light, Balanced or Strong
- 3Compress, check the new size, then download
Questions
Which level should I use?
Balanced suits most documents. Use Strong for email attachments with many photos, and Light when print quality matters.
Will text become blurry?
No. Text and vector graphics stay sharp at every level; only embedded images are compressed.
Why is the size unchanged?
Some PDFs contain little that can be compressed, for example text-only documents that are already optimised.