A PDF that has grown to 30 or 40 MB is usually not a text problem. The words and fonts in a hundred typed pages rarely weigh more than a couple of megabytes; the weight is almost always the images — scans, phone photos, screenshots or print-resolution artwork.
That means compression is a choice about images, not a magic button. This guide shows how to choose the trade-off and how to check the result.
Step by step
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1
Upload your PDF
Drag your PDF onto the box or click Choose file. It is sent over an encrypted connection and only used for this task.
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2
Set the options
Adjust image quality, image resolution (ppi), image conversion and multimedia files. Every field has a sensible default, so you can usually run the tool straight away.
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3
Pick the trade-off
Higher compression means smaller files and softer images. Try the middle setting first — it usually halves the size with no visible change.
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4
Run it and download
Press Compress and the page shows progress while it works. When it finishes you get a download link — nothing is emailed and nothing is stored longer than it needs to be.
Where the weight actually lives
Run a simple test: if you can select the text in your PDF viewer, the words are text and compression can preserve them perfectly. If the page is one big picture, every letter is pixels, and making the file smaller means reducing or re-encoding those pixels. Compress PDF shows the finished size before you commit, so you can see the effect instead of guessing.
Two different problems can look like “the PDF is too big”. A bloated scan needs image compression; a text PDF with a few huge embedded photos needs those images resampled. Both are handled by the same compression pass, but the right level differs.
Pick the level by where the file is going
- Email or a web form — choose the strongest setting that keeps the text readable. For a scan of a receipt, that is usually the smallest output.
- Normal screen reading and office printing — the recommended middle setting usually cuts the size by more than half with no visible difference at 100%.
- Professional print or photography — use low compression, or skip it. A print shop would rather receive a large file than a soft one.
Do not compress an already-compressed file repeatedly. Each pass spends more quality for less size gain; keep the original and go back to it if the first result is not right.
Check both size and readability
After compressing, open the output at 100% and look at a dense paragraph, a small table and the lightest line in the document. Zoom checks matter because a thumbnail can hide blockiness. Then check the file size in your file manager or the tool’s inspector — the percentage saved is the number that decides whether the upload will pass.
If the text is now fuzzy but the images were fine, the original was probably a scan; run OCR first to add a text layer, then keep the searchable PDF rather than compressing the picture further. OCR PDF explains the privacy difference: its recognition runs in your browser.
When compression is the wrong tool
If the document is huge because it contains hundreds of pages you do not need, delete or extract pages instead of squeezing them. If the images are print-resolution artwork that must stay sharp, splitting the file may solve the upload limit without touching quality. Compression is for files whose content is already the right content.
Good habits for Compress
- Compress is the quickest win for an oversized file — try it before resizing images by hand.
- Flatten before sending a form if you want the answers frozen.
- Repair first if a file refuses to open; many other tools then work on it.
Common questions
Is this tool free?
Yes. Every tool on this site is free to use, with no sign-up, no watermark and no daily task limit.
Do I need to install anything?
No. The tools run in your browser and are processed by this server.
What happens to my files?
They are stored under an unguessable id and swept automatically after a couple of hours. Nothing is shared or indexed.
Does it work on a phone?
Yes. The page pickers and editors are built for touch, so dragging, rotating and selecting pages all work without a mouse.
What does Compress do exactly?
Pick a quality level and we shrink the file size.
Does compression delete text or make it unsearchable?
No. Text stays text and remains selectable and searchable. The visible quality loss, when there is any, comes from the images.
Can I compress a password-protected PDF?
Unlock a copy first if you have the password, then compress it. Compression cannot open a document it is not allowed to read.
How small will my PDF get?
It depends on what is inside. Scans and photos often shrink by 60–90%; text-only PDFs may barely change because they were already small. The size inspector shows the real result before you save.