Is there a file size limit when compressing a PDF?

Free users can compress single PDFs up to 50 MB at a time. Premium lifts that to 100 MB single files plus batch compression of multiple PDFs at once. Compression runs in your browser, so the practical ceiling is whatever your machine's memory can hold — even very large reports go through without problems on a modern laptop.

Are my files private when I compress a PDF here?

Yes — compression runs entirely in your browser. Your PDF is never uploaded to PDFly's servers or shared with any third party; the compressed file is generated locally from your original. That's why even contracts and medical records can go through this flow without leaving your device.

Can I undo the compression and get the original quality back?

Compression discards data — once an image is re-encoded at lower quality, that detail can't come back from the compressed file. The good news: your original PDF is never modified. Keep the source file and you can always re-run compression with a different setting (Basic instead of Strong, for example) until you're happy with the trade-off.

How to compress a PDF

Shrink a PDF so it fits inside an email attachment limit, uploads faster, or takes less space on disk. PDFly compresses your file in the browser and lets you choose between gentle quality-first compression and a stronger setting that produces the smallest possible output.

Last updated: April 29, 20261 min read

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Step 1 — Open the Compress tool
Open the Compress tool. You'll see the upload screen titled "Compress PDF".
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Step 2 — Upload your PDF
Click "Choose PDF Files" and pick a PDF, or drag one onto the page. Anything works — invoices, slide decks, scanned reports, exported designs.
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Step 3 — Choose a compression level
Pick a compression level. "Basic" keeps text crisp and images close to the original quality; "Strong" produces the smallest file by re-encoding images more aggressively — best when size matters more than pixel-perfect fidelity.
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Step 4 — Compress and download
Click "Compress File" to start, then "Download File" when it's ready. PDFly shows you the savings — the original size, the compressed size, and the percentage shaved off — before you download.

How to compress a PDF

Step 1 — Open the Compress tool

Step 2 — Upload your PDF

Step 3 — Choose a compression level

Step 4 — Compress and download

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