About this tool
Compress PDF makes a PDF smaller so it fits an email attachment limit or an upload form. You choose one of three levels, and the tool shows you the size before and after so you can judge whether it was enough.
The file is never uploaded. Compression runs inside your browser, on your machine. This matters more here than with most tools — the files people need to shrink are usually the ones they would least like to put on somebody else's server: contracts, bank statements, medical scans, ID documents.
The three levels, and what they actually do
This is the part worth reading before you choose, because the levels are not simply "a bit smaller" and "a lot smaller". They work differently.
- Light — tidies up the file's internal structure without touching how the pages are drawn. Your text stays real text: selectable, copyable, searchable. The saving is modest, and on an already-tidy PDF it may be small.
- Medium — re-draws each page as a JPEG image at a reduced resolution and quality. The size drop is large. The text becomes part of a picture, so it is no longer selectable or searchable.
- Strong — the same approach as Medium, pushed further: lower resolution, lower quality, smallest file. Good for getting under a stubborn size limit; visibly softer on screen.
How to use this tool
- Select the PDF you want to shrink.
- Choose Light, Medium or Strong.
- Download the smaller file. The before and after sizes are shown, so you can see what you gained.
Which level should you pick?
Work backwards from what the file is for.
- A document someone will search, quote or copy from — a report, a contract, a thesis: use Light. Keeping the text real is worth more than the megabytes.
- A scan you just need to send — a signed form, a receipt, a photographed document: Medium is usually the sweet spot. It was already a picture, so nothing is lost that you had.
- Up against a hard limit — a portal that refuses anything over 2 MB: Strong, then check it is still readable before you send it.
- Anything going for OCR later, or into a legal or archival record: Light, or do not compress at all. Medium and Strong throw away detail that OCR needs.
What you cannot undo
Medium and Strong are one-way. Once a page has been re-drawn as a reduced JPEG, the original text and detail are gone from that copy — compressing again at Light will not bring them back.
So: keep your original. The tool gives you a new file and leaves the one on your disk untouched, which is exactly how it should be. Do not delete the original until you are sure the compressed version is good enough for what you need.
How it works
Why some PDFs barely shrink
It depends entirely on what is making the file big, and there are only a few usual culprits:
- Scanned pages and photographs. These are where the weight is, and where compression wins big — a scan-heavy file can drop by most of its size.
- Pure text with embedded fonts. A 40-page text report is already small and already efficient. There is very little to remove, so Light will hardly change it. That is not a failure; the file was fine.
- A PDF that was compressed before. Running it again gives you little and costs you quality.
If Light gives you nothing, that is the tool telling you the file is already about as small as it can be while staying a text document. The only way further down is Medium, and that trade is a real one.
If the document will be printed
Screens are forgiving; paper is not. A file compressed at Strong often looks acceptable on a monitor and disappointing when printed, because printing uses far more detail per inch than a screen shows. If the document is going to be printed, use Light, or Medium at most, and print one test page before committing to a hundred.