How to Compress Images on Mac: Every Method Compared

Updated June 2026 · 6 min read

Macs are known for handling images well — but macOS doesn't make image compression obvious. There are actually six different ways to compress images on a Mac, ranging from built-in tools you already have to powerful command-line utilities. Here's every method, compared.

Method 1: Preview (Built-in, Best for Single Images)

Every Mac comes with Preview, and it has a hidden image compression feature:

1. Open your image in Preview
2. Go to File → Export (not Save — Export is different)
3. Choose JPEG as the format
4. Drag the Quality slider (try 70-80%)
5. Click Save

Limitations: No batch processing. Only JPEG quality control — you can't compress PNG files while keeping them as PNG. No WebP or AVIF export.

Method 2: Sips Terminal Command (Best for Batch)

macOS includes a powerful command-line tool called sips (Scriptable Image Processing System). It can batch-resize and convert images without installing anything:

sips -Z 1200 *.jpg — Resize all JPGs to 1200px max dimension

sips -s format jpeg -s formatOptions 80 *.png --out output/ — Convert all PNGs to JPG at 80% quality

Limitations: Command line only. No WebP/AVIF support. Cannot optimize PNG (only convert away from PNG).

Method 3: ImageOptim (Free App, Best for PNG Optimization)

ImageOptim is a free Mac app that losslessly compresses PNG, JPEG, and GIF files by stripping metadata and applying advanced compression algorithms:

• Drag and drop interface
• Lossless — quality is identical to the original
• Typical PNG reduction: 20-40%
• Also strips EXIF data for privacy

Limitations: Lossless only — you can't do aggressive "good enough" compression. No WebP/AVIF support. Mac-only.

Method 4: Browser-Based Compressor (Best All-Rounder)

A browser compressor like compress2png.com works on Mac without installing anything:

• Drag and drop images directly from Finder
• Batch processing — 50+ files at once with ZIP download
• Multiple output formats: JPG, PNG, WebP, AVIF
• Quality slider with live preview
• No upload — everything processes locally in your browser

This combines the ease of Preview with the power of dedicated apps, and works identically on Mac, Windows, and Linux.

Method 5: Shortcuts App (Built-in Automation)

macOS Monterey and later include the Shortcuts app, which can automate image compression:

1. Open Shortcuts
2. Create a new shortcut with: Get Images from Input → Convert Image (JPEG, 80%) → Save File
3. Pin it to the menu bar or right-click Services menu

Great for repeat workflows — right-click any image in Finder → Services → Your Compression Shortcut.

Method 6: Affinity Photo / Photoshop (For Professionals)

If you already own pro editing software, both offer detailed export controls including color profile management, metadata control, and format-specific tuning. Overkill for simple compression, but necessary if color accuracy is critical.

Comparison Table