Best solution
After testing various PDF compression methods, I've found that specialized PDF apps consistently outperform built-in macOS utilities when quality matters. But free tools have their place too, especially for quick, one-off compressions where perfection isn't critical.
Here's a summary of the compression methods I tested, showing real-world results from test files:
| The tool I used | Compression rate I got | Quality loss | Works best for | Price |
| PDF Squeezer from Setapp | Up to 92>#/p### | Minimal to moderate | Batch processing, quality control | From $14.99 USD/mo + tax with Setapp Membership or from $19.99 US + tax standalone |
| Nitro PDF Pro from Setapp | 83>#/p### | Minimal | Image-heavy PDFs | From $14.99 USD/mo + tax with Setapp Membership |
| Adobe Acrobat Pro | Up to 80>#/p### | Minimal | Professional workflows | $19.99 USD/month |
| Preview (macOS) | 64>#/p### | Noticeable | Quick text-only PDFs | Free |
| ColorSync Utility | 64>#/p### | Noticeable | Basic compression | Free |
| Online tools | 68-93>#/p### | Variable | One-time use | Free with limits |
*Setapp is a platform with 300+ apps for macOS, iOS, and web. Try it free for 7 days.
The iPhone's built-in compression feature is misleading. When you long-press a PDF in Files and tap Compress, it creates a ZIP file rather than actually reducing the PDF size. My 7.3 MB test file became a 7.1 MB ZIP.
For real compression on the iPhone, I use PDF Squeezer from Setapp. It works offline, protects your privacy, and achieves up to 83% compression. In my tests, Moderate mode compressed files by 41% while Strong mode hit 83%.
To compress PDFs with PDF Squeezer on iPhone:
1. Install and open PDF Squeezer.
2. Tap Add files > Files.
3. Select your PDF from Files > Tap Open.
4. Wait for automatic compression to complete.
The app defaults to Moderate compression, but you can switch to Light for minimal quality loss or Strong for maximum size reduction. Your compressed file saves directly to your device; no cloud uploads required.
PDF Squeezer delivers the best compression-to-quality ratio I've found on Mac. It handles entire folders at once, preserves password protection, and keeps images sharp. The app works entirely offline, so sensitive documents never leave your Mac.
Here's how to compress PDFs with PDF Squeezer on Mac:
1. Install and open PDF Squeezer on your Mac.
2. Drop your PDF into the app window.
3. Choose your compression level from the drop-down (Light, Medium, or Strong).
4. Click Save to export your compressed file.
In my testing, medium compression reduced a 7.8 MB file to 1.6 MB (78% reduction) with minimal quality loss. The app includes advanced tools such as extracting images and text. Look for the "i" and paper icons in the top-right corner.
Or buy PDF Squeezer as a standalone app on Setapp Marketplace.
Scanned PDFs are notoriously large because scanners capture pages as high-resolution images at 300 DPI. That's far more resolution than any screen needs.
I prevent this problem by scanning with Prizmo from Setapp instead of traditional scanners. Prizmo uses your iPhone as a scanner and optimizes file size during capture. As long as your devices share the same Wi-Fi, you can snap a photo, and Prizmo converts it to a clean, compact PDF without watermarks.
If you're not sure how to set up scanning on your Mac, here's how to scan a document on Mac using Prizmo and other tools.
Nitro PDF Pro offers another solution for existing scanned PDFs. It imports directly from scanners or iPhones and includes comprehensive PDF tools beyond compression.
To reduce scanned PDF size with Nitro PDF Pro:
1. Install and open Nitro PDF Pro.
2. Click Open File.
3. Choose your scanned PDF > Click Open.
4. Go to File > Create Optimized PDF.
5. Choose your optimization settings > Click Optimize.
6. Click OK on the results notice.
7. Go to File > Save to save your optimized PDF.
The app intelligently optimizes images while preserving text clarity and document structure.
The file size went from 6.5 MB to 1.3 MB (83% compression). Images lost a little sharpness but stayed professional-looking.
Both Nitro PDF Pro and Prizmo are available on Setapp with a 7-day free trial, so you can try both of them to see which one works best for you.
Preview, macOS's built-in PDF viewer, includes basic compression. While not ideal for image-heavy documents, it works adequately for text-based PDFs.
To compress PDF files with Preview:
Open your PDF in Preview (double-click the file).
Go to File > Export.
Choose PDF from the Format drop-down.
Choose Reduce File Size from the Quartz Filter drop-down.
5. Choose your save location and click Save.
Preview's compression is conservative but preserves text readability well. The file size reduced from 7.8 MB to 2.8 MB (64% reduction). Image quality dropped noticeably.
ColorSync Utility offers another free compression option built into macOS. Like Preview, it compresses by reducing image quality, making it unsuitable for documents where visuals matter.
To use ColorSync Utility:
Open ColorSync Utility from Applications > Utilities.
Go to File > Open and choose your PDF.
Choose Reduce File Size from the Filter drop-down
4. Click Apply.
5. Go to File > Save to export your compressed PDF.
The file size reduced from 7.8 MB to 2.8 MB (64% compression). Image quality loss was noticeable, similar to Preview.
ColorSync provides slightly different compression algorithms than Preview, sometimes yielding better results for specific file types.
Adobe offers a free online PDF compressor that delivers impressive results. Unlike many online tools, Adobe's compressor maintains good image quality while significantly reducing file size.
To use Adobe's online compressor:
In my test, Adobe's tool achieved 77% compression (from 7.8 MB to 1.8 MB) while maintaining surprisingly good image quality.
Adobe Acrobat Pro offers the most comprehensive PDF compression features, though it comes with a steeper learning curve and paid subscription. The software provides precise control over compression settings and batch processing capabilities.
To compress PDFs in Acrobat Pro:
Acrobat Pro excels at maintaining quality while achieving substantial compression, making it popular for professional workflows.
Smart compression starts before you hit the compress button. These strategies help minimize file size from the start:
Optimize images before adding them to PDFs using an app like Squash from Setapp for precise control. I use it to reduce image size, compress images, or apply color correction and filters. You can test Squash with Setapp free trial, too.
After testing numerous compression methods, two solutions consistently deliver the best balance of size reduction and quality preservation: PDF Squeezer and Adobe Acrobat.
Remember that compression isn't always necessary. You can reduce file size during document creation by:
These preventive measures often eliminate the need for aggressive compression later.
PDF Squeezer, Prizmo, Squash, Nitro PDF Pro, and PDF Search are all available on Setapp — one subscription gives you access to 300+ apps for Mac and iPhone, starting from $14.99 USD/mo + tax. Start your free 7-day trial and put all five to work today.
PDF stands for Portable Document Format. Adobe created it so files keep their fonts, images, and layout across devices and operating systems. Because nothing shifts, PDFs are perfect for sharing contracts, reports, and manuals. The downside: high-resolution images inside PDFs can make files heavy and harder to send.
Three main approaches work well: use Preview on Mac for basic compression (File > Export > Reduce File Size), try PDF Squeezer for better quality retention and batch processing, or upload to free online tools if the file isn't sensitive. Each method trades some quality for smaller size.
Yes, compression always involves some quality trade-off. Light compression (10-30% reduction) barely affects quality. Medium compression (50-70%) may show slight image degradation. Heavy compression (80%+) noticeably reduces image quality but keeps text readable. Choose based on your document's purpose.
PDF Squeezer processes entire folders automatically — just drop a folder into the app. Adobe Acrobat Pro also supports batch compression with its AutoBatch plug-in. Online tools typically handle one file at a time unless you pay for premium features.
Free online compressors upload your files to their servers, creating privacy risks for sensitive documents. Most delete files after processing, but policies vary. For confidential files, use offline tools like PDF Squeezer or built-in Mac utilities that process everything locally.
Scan at 150 DPI for screen viewing instead of 300 DPI. Use OCR software like Prizmo to convert scanned images to searchable text, which compresses better. This approach can reduce file size by 70% while keeping text sharp and searchable.
Security-tested
Best solution
