How to Compress a PDF File on Mac (3 Free Methods)

You have a 45MB PDF that needs to go out via email, but your mail client caps attachments at 25MB. If you are on a Mac, you have a few options to shrink that file down. In this guide we will walk through three free ways to compress a PDF file on Mac, starting with the quickest.

Method 1: Compress PDF Online (Works on Mac, Windows, and Mobile)

The fastest way to compress a PDF on Mac is to use an online tool. No downloads, no Homebrew packages, no Terminal commands.

1. Open Compress PDF in Safari or any browser on your Mac.
2. Drag your PDF into the upload area, or click to select the file.
3. Choose your compression level. For most email use cases, the default "Recommended" setting cuts file size by 60-80% while keeping the document readable.
4. Click Compress PDF and download your smaller file.

This method works whether you are on a MacBook, iMac, or even an iPad. Since the compression runs on the server, it handles large files that might slow down your Mac's Preview app.

Method 2: Use Preview (Built Into macOS)

Every Mac ships with Preview, and it has a basic "Reduce File Size" export option. Here is how to use it:

1. Open your PDF in Preview (right-click the file > Open With > Preview).
2. Go to File > Export.
3. In the Quartz Filter dropdown, select Reduce File Size.
4. Choose where to save and click Save.

The catch: Preview's compression is aggressive. It downsizes images significantly, which can make photos and charts look blurry. There is no way to control the compression level. For text-heavy documents like contracts or forms, this works fine. For anything with images, you will probably want more control.

Method 3: Automator (Batch Compression)

If you regularly compress PDF files on Mac, you can set up an Automator workflow so it happens in two clicks:

1. Open Automator (search for it in Spotlight).
2. Choose Quick Action as the document type.
3. Set "Workflow receives current" to PDF files in Finder.
4. Add the Apply Quartz Filter to PDF Documents action.
5. Select Reduce File Size as the filter.
6. Save with a name like "Compress PDF."

Now you can right-click any PDF in Finder, go to Quick Actions, and hit your Compress PDF workflow. Same limitations as Preview (no quality control), but it saves a few clicks if you do this often.

Which Method Should You Use?

Method	Best For	Quality Control	File Size Limit
ToolifyPDF	Any document, especially with images	Yes (multiple levels)	Up to 200MB
Preview	Text-heavy documents without images	No	No limit (local)
Automator	Batch compressing many files at once	No	No limit (local)

For most people, using an online compressor gives the best balance of file size reduction and quality. Preview is a solid backup for quick, text-only documents when you are offline.

Frequently Asked Questions

Does compressing a PDF reduce quality? It depends on the compression level. Light compression reduces file size with almost no visible quality loss. Heavy compression can make images look softer, but text stays sharp regardless.

Can I compress a PDF on Mac without losing quality? Yes. ToolifyPDF offers multiple compression levels. The "Low Compression" setting reduces file size slightly while preserving original image quality.

Is there a way to compress PDF on Mac without installing software? Yes, that is exactly what online tools like ToolifyPDF are built for. Open it in your browser, upload, compress, and download. Nothing to install.

Does this work on Windows and Linux too? Yes. While this guide focuses on Mac, ToolifyPDF runs in any browser on any operating system. The steps are identical.

Wrapping Up

You do not need expensive software to compress a PDF on Mac. Preview handles basic cases, Automator can batch-process files, and an online tool gives you the most control over the output quality. Pick the method that fits your workflow and stop fighting with oversized attachments.