Scanned document that will not attach
- Input
- scan.pdf, 18.4 MB, Balanced
- Output
- About 2-4 MB, comfortably under a 10 MB mail limit
Scans are photographs of paper. Lowering image resolution is where nearly all the saving comes from.
Compress PDF
Compressing a PDF reduces its file size, usually by re-encoding the images inside it at a lower resolution. Pick a level, and the tool reports the original size, the new size and the percentage saved so you can judge the trade-off. Text and vector graphics stay sharp at every level.
Compression runs entirely in your browser. Your file is never uploaded.
How to
How to use Compress PDF
- 1
Upload the PDF
Drop a PDF onto the upload area or click to browse. The current file size is shown immediately.
- 2
Pick a level
Lossless rebuilds the file and keeps text selectable. Balanced, Strong and Maximum re-encode each page as an image, trading searchable text for a much smaller file.
- 3
Compress
Click Compress PDF and wait for the result. Larger scanned documents take longer.
- 4
Check the saving, then download
Compare the before and after sizes. If the saving is too small, try a stronger level; if the pages look soft, step back down.
Examples
Compress PDF examples
Text-only document
- Input
- invoice.pdf, 240 KB, Maximum
- Output
- Roughly 230 KB — very little change
There are no photos to shrink. A PDF that is mostly text is already small, and compression has little left to remove.
Keeping print quality
- Input
- brochure.pdf, 12 MB, Lossless
- Output
- Around 11 MB with images untouched
Lossless rebuilds the document from its parsed objects, dropping orphaned data and old revisions. Choose it when the PDF is going to a printer.
Why use it
What Compress PDF gives you
Real, measurable levels
Each level maps to a specific image resolution, so the difference between them is visible in the output size.
You see the result first
Original size, compressed size and percentage saved are shown before you commit to the download.
Text never gets blurry
Only raster images are re-encoded. Text and vector graphics are left as they are and stay crisp at any zoom.
A private option
Every level runs in your browser and nothing is sent anywhere, so even a sensitive contract can be compressed safely.
No watermark
Nothing is stamped onto the compressed file and there is no daily cap.
Good to know
Compress PDF limitations
- Levels other than Lossless re-encode each page as an image, so text stops being selectable and searchable in the result.
- Strong compression can occasionally produce a larger file on an already-optimised PDF. When that happens the tool tells you and hands back your original.
- A PDF that is mostly text will barely shrink — there are no large images to re-encode.
- Maximum renders pages at 80% of natural size. Printed output at that level will look soft.
- Compression cannot be undone. Keep your original if you may need the full-resolution version.
Summary
Compress PDF in short
- Compression saves space mainly by lowering the resolution of embedded images.
- Balanced, Strong and Maximum render pages at roughly 150%, 110% and 80% of natural size before re-encoding them as JPEG.
- Scanned documents shrink dramatically; text-only PDFs barely change.
- Text and vector graphics stay sharp at every level.
FAQ
Compress PDF questions
How does PDF compression actually work?
Most of a large PDF is embedded images. Compression decodes those images, resamples them to a lower resolution and re-encodes them. Text and vector art are stored as instructions, not pixels, so they are left alone.
Which level should I choose?
Balanced for documents you will print, Strong for email and sharing, Maximum for screen-only reading. Use Lossless whenever the text must stay selectable.
Why did my PDF barely get smaller?
It is probably already efficient. Text-only PDFs contain no large images, so there is very little to remove. Compression helps most with scans and image-heavy documents.
Will my text become blurry?
No. Text is stored as font instructions rather than pixels, so it renders sharply at any zoom regardless of the level you pick. Only photographs and scans lose detail.
Is my PDF uploaded when compressing?
No. Every level runs in your browser using its own PDF engine. Nothing is transmitted, so a contract or a scanned passport stays on your machine — there is no server to hold it and nothing to delete afterwards.
Can I undo compression?
No. Detail removed from an image cannot be restored. Keep the original file if you might need the full-quality version later.
What is the file size limit?
50 MB per file. If your document is larger, split it first, compress the parts, then merge them back together.
Why are scanned PDFs so large?
A scanner stores each page as a full-page photograph, often at 300 DPI or higher. Ten scanned pages can easily exceed 20 MB, while ten pages of typed text might be 100 KB.
What size do I need for email?
Most mail providers cap attachments at 20-25 MB, and many corporate systems at 10 MB. The Balanced level usually brings a large scan under 10 MB.
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