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Compress a PDF in Adobe Acrobat

Acrobat has two routes: a one-click option that handles most cases, and an advanced panel for when you need to hit a specific size. Here is where both of them live.

You need Acrobat, not Reader. Both methods below are features of Adobe Acrobat (the paid application). The free Adobe Acrobat Reader cannot compress a PDF on your computer — if that is what you have, see compressing a PDF in Adobe Reader.

The quick way: Reduced Size PDF

This applies Adobe's standard compression in one step. It is the right choice most of the time, and it keeps your text selectable.

Windows

  1. With your PDF open, go to Menu Save as Other Reduced Size PDF
  2. In the dialog, pick a version from the Make compatible with menu. Choose the oldest version everyone who needs the file can open — but note that older versions have fewer compression features available, so the file will not shrink as far.
  3. Select OK.
  4. Choose where to save, give it a filename, and select Save.

macOS

  1. Go to File Save as Other Reduced Size PDF
  2. Pick a version from Make compatible with.
  3. Select OK, then choose a location and select Save.

The precise way: Optimized PDF

When Reduced Size PDF does not shrink the file enough, the PDF Optimizer lets you decide exactly what gets sacrificed. It is the same dialog on both platforms; only the way in differs.

  1. On Windows go to Menu Save as Other Optimized PDF — on macOS, File Save as Other Optimized PDF
  2. Choose Standard from the Settings menu as your starting point.
  3. Adjust the panels on the left. Each one trades something different:
    • Images — downsamples and compresses pictures. This is where the large savings are in almost every document.
    • Fonts — unembeds or subsets fonts. Saves a little, but unembedding risks the document looking different on another machine.
    • Transparency — flattens transparency effects and lowers their quality.
    • Discard Objects — strips embedded thumbnails, search indexes, and flattens form fields.
    • Discard User Data — removes comments, form data, multimedia and private information.
    • Clean Up — removes invalid bookmarks and links, and prepares the file for fast web viewing.
  4. Set Make compatible with, select OK, then save.
Start with Images. In a document that will not shrink, the cause is almost always high-resolution pictures. Downsampling images to 150 ppi is usually invisible on screen and often cuts the file by more than half. Work through the other panels only if that is not enough.

Compressing several PDFs at once

Acrobat can apply the same settings across a batch, which saves a lot of clicking when you have a folder of scans.

  1. Open Menu / File Save as Other Reduced Size PDF
  2. Choose your compatibility setting, then select Apply to Multiple Files.
  3. In the Arrange documents dialog, use Add Files or Add Open Files to build the list.
  4. Select OK, then set the output folder, filename pattern and overwrite behaviour in Output Options.
  5. Select OK to run the batch.

Why your file still will not shrink

A few causes come up repeatedly. If the PDF is mostly vector graphics or plain text, there is very little to compress — the file is already near its floor, and no setting will change that. If it contains scanned pages, the images are the whole document, so image downsampling is the only lever that matters. And if you chose an old compatibility version, you have switched off the newer compression methods; try again with a more recent one.

No copy of Acrobat?

Adobe's online compressor is free for occasional use and offers High, Medium and Low compression levels, handling files up to 2 GB. The trade-off is that your document is uploaded to Adobe's servers for processing. For anything confidential, that may matter to you.

Our own PDF compressor takes a different approach: you set a target size in kilobytes or megabytes, and it works to fit it. It runs entirely inside your browser, so the file never leaves your computer. The trade-off there is that pages are converted to images, so text stops being selectable.

Menu paths verified against Adobe's own documentation, October 2026.

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