Compression is a trade-off, not a magic switch
A PDF can contain text, vector drawings, fonts, metadata and raster images. The biggest reductions come from image-heavy scans and presentations. A mostly textual PDF may already be compact, so a small reduction is a normal result rather than a failed run.
The three levels, and when to use each
| Level | What it does | Use it when |
|---|---|---|
| Light | Re-saves the file with a leaner structure and clears the title, author and other properties. Images and text are not changed. | The PDF is mostly text, is already optimized, or its images must stay exactly as they are. |
| Balanced (recommended) | Recompresses large embedded images to JPEG (scaled down to at most 1600 px) and tidies the structure. Text stays selectable. | You are sending a mixed text-and-image PDF by email or storing it. |
| Maximum | Renders every page as an image at 150 DPI. The biggest reduction, but text may not stay selectable. | You only need to read the document and size is the priority, such as a large scan. |
How to compress a PDF without losing quality
- Keep the original file as a backup.
- Open Compress PDF, add the file and start with Balanced.
- Download the new copy and compare its size with the original.
- Open pages with small text, charts and photos at normal reading size.
- If something looks soft, go back and choose Light. If it is still too large and readability allows, try Maximum.
If the result says the file was already well optimized, believe it: the quality-safe savings are gone, and the next step is to cut pages or split the file rather than squeeze harder.
Compress a PDF for email
Work backwards from the limit. Check the actual size of the compressed file in your file manager rather than the size you started with. Mail systems encode attachments for transport, which adds roughly a third, so a 20 MB file can arrive as about 27 MB. Leave headroom, and if the file still does not fit, split it and send the parts in separate messages.
What to inspect after compression
- Small text in tables, footnotes and scanned pages.
- Photographs, signatures, diagrams and fine lines.
- Page count, orientation, links, annotations and form fields.
- Document properties: Light and Balanced clear the title, author and keywords, so add them back if you rely on them.
- Whether the final size meets the actual upload or email limit.
Scans, forms and signed files
- Scans. Already pictures of pages, so Balanced usually saves the most. Maximum renders each page at 150 DPI, which is fine for reading but can soften small print.
- Forms and links. Maximum rebuilds every page as an image, so fillable fields and clickable links stop working. Use Balanced or Light if the file must stay interactive.
- Signed files. Any recompression creates a new file, so a digital signature on the original will not remain valid. Compress first, then sign.
When removing or splitting is better
Dropping unneeded pages with Delete Pages shrinks a file without touching quality at all. If a long document must stay readable and the recipient accepts several attachments, split it into logical sections instead of compressing hard. The upload-limit decision tree walks through the order to try these in.
People also ask
Common questions
Which compression level should I choose?
Start with Balanced. Use Light for mostly-text PDFs or files whose images must stay exactly as they are. Use Maximum only when size matters more than quality, for example a scan you only need to read.
Will the text still be selectable after compression?
With Balanced and Light, yes. With Maximum, pages are turned into images, so text may no longer be selectable or searchable.
Why did compression barely reduce my PDF?
Text-heavy PDFs and already-optimized files have little removable data. FreePDFKit tells you when a file was already well optimized and its size did not decrease. Image-heavy scans usually offer more room.
Does PDF compression always reduce quality?
Not necessarily. Light leaves images and text untouched, Balanced recompresses large images, and Maximum turns every page into an image, which can soften small text. Always inspect the result.
How small should a PDF be for email?
It depends on the provider and the recipient’s system. Many cap attachments somewhere around 20–25 MB and some company gateways are lower. Email adds encoding overhead of roughly a third, so aim comfortably under the limit.
What if the compressed PDF is still too large?
Delete pages you do not need, split the document into logical parts, or use a stronger level if readability stays acceptable.