Compress PDF
Compress PDF files online free. Shrink big PDFs up to 90% smaller for email and uploads. No file upload — compression happens on your device.
The 10-second test: switch off your Wi-Fi (or turn on airplane mode) and use this tool anyway. It keeps working — because there is no server doing the work.
The technical check: open your browser's developer tools, go to the Network tab, and run the tool. Your file is never sent anywhere.
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How to compress a PDF
Pick your PDF, choose a compression level, and download a much smaller file — scanned documents often shrink by 80-90%. Perfect for email attachment limits and website upload caps. Your file is compressed right on your device, never sent to a server.
What compression actually changes
Almost all of a large PDF's size is images. Text, even hundreds of pages of it, takes up very little space — a 200-page text document is often under 1 MB, while a single high-resolution scan of one page can exceed 5 MB. Compression works by reducing the resolution and quality of the embedded images and leaving the text layer untouched. That is why scanned documents shrink dramatically and text-based PDFs sometimes barely move.
Choosing a level
Low barely touches the images and is for when you need a small reduction with no visible change at all. Recommended is the right default: a large reduction, with quality that still looks right on screen and prints acceptably. Extreme is for hitting a hard upload limit — text stays readable, but photographs and fine detail visibly soften.
When a PDF will not get smaller
If your file is already optimised, compressing it again can produce a larger file, because re-encoding already-compressed images adds overhead without removing much. This tool detects that case and keeps your original rather than handing you something worse. If you genuinely need a smaller file at that point, remove pages you do not need or split the document.
Hitting an exact size limit
Upload forms usually specify a hard cap. Go straight to the page for your target: 50 KB · 100 KB · 200 KB · 500 KB · 1 MB · 2 MB. Each opens this tool with the right level already selected.
Fixing the problem at the source
If you are scanning documents yourself, scanning at 200 DPI instead of 600 DPI reduces the file to roughly a ninth of the size before compression is even involved, with no visible difference for ordinary text documents. Most scanner software defaults far higher than anyone needs.
Quick presets
Frequently asked questions
How much smaller will my PDF get?
It depends on the content. Scanned and image-heavy PDFs often shrink 80-90%. PDFs that are already lean may not compress further — in that case everySIMPLEtool keeps your original instead of making it bigger.
Does compressing reduce quality?
Slightly, depending on the level you pick. "Recommended" keeps documents crisp and readable; "Extreme" trades more quality for the smallest size.
Why compress a PDF?
Smaller files send faster, fit under email attachment limits (usually 25 MB) and upload successfully to portals with strict size caps.
Why did my PDF get bigger instead of smaller?
Because it was already optimised — re-encoding compressed images adds overhead. This tool detects that and keeps your original file instead.
Does compressing a PDF make the text blurry?
No. Text is stored as text, not as an image, and is left untouched. Only embedded images are re-encoded, so what softens is photographs and fine graphic detail.
What is the best DPI for scanning documents?
200 DPI is plenty for ordinary text documents and produces roughly a ninth of the file size of a 600 DPI scan. Use 300 DPI if the document contains small print or fine detail.
Can I compress a PDF without losing any quality at all?
Only marginally. Truly lossless savings come from removing unused resources, which yields a few percent. Meaningful reduction always involves reducing image quality somewhere.