Compress a PDF on iPhone or Mac

2026-10-10

Compress PDF runs in the browser you already have. The PDF is read and compressed on your device; it isn’t uploaded to a server, and you don’t need an account or an app.

On iPhone or iPad

1. Open Compress PDF in Safari (or any browser) and tap Choose PDF. You can pick a file from Files, iCloud Drive or another storage provider.
2. Keep Balanced or choose another level, then tap Prepare PDF.
3. When it’s ready, tap Save or share and choose where the PDF goes — for example Save to Files, Mail or a messaging app.

If sharing doesn’t open, use Open PDF: the compressed PDF opens in a new tab, and you can save it from the browser’s share button. The page says “sent to the destination you chose” rather than “saved”, because a website can’t see where you put it.

Large files: compressing happens in your phone’s memory. A PDF of several hundred pages or well over 50 MB can take a while, and on older iPhones it may not fit. If that happens you’ll see a clear message; splitting the PDF first with Split PDF usually solves it.

On a Mac

1. Open Compress PDF in Safari, Chrome or Firefox and drop the PDF on the page, or click Choose PDF.
2. Choose a level and click Compress PDF. The compressed copy downloads automatically and ends in -compressed.pdf.
3. If the browser didn’t start the download, click Download PDF.

Your original file is never changed, on any device.

What about Preview’s “Reduce File Size”?

Preview on the Mac has a Reduce File Size filter in its export options. It has no level to choose from. Compress PDF gives you three levels, keeps text, links, form fields and bookmarks as they are, checks the result before giving it to you, and tells you when a file is already as compact as it reasonably gets.

A signed PDF

If the PDF has a digital signature, Compress PDF asks first. Any change to a signed PDF makes the existing signature invalid, so the compressed copy is unsigned. You can cancel and keep using the original.