How to compress JPEG files on a Mac
JPEG is already a compressed format, so shrinking it further is a balancing act: save too little and the file stays big, push too far and photos get blocky. Here are three ways to do it on macOS — and the trick that saves the most.
1. Preview's quality slider
Open the photo in Preview and choose File → Export…. With JPEG selected you get a Quality slider and a live file-size estimate. Moving it from "Best" to somewhere in the middle usually cuts the size a lot with little visible change. It's one photo at a time, though, and it's easy to overdo it.
2. Export smaller from Photos
In the Photos app, select your pictures and choose File → Export → Export Photos…. You can pick JPEG quality and a smaller size (for example "Large" instead of "Full Size"). Great for sharing a set of photos, but you can only start from photos in your library.
3. TinyPresso for batches — and the bigger win
Drag any number of JPEGs into TinyPresso and it re-saves them at a sensible quality that keeps them looking the same. In our test, a high-quality 1400×1045 landscape photo went from 577 KB to 420 KB (−27%). If a JPEG is already well compressed, TinyPresso keeps the original instead of making it worse.
The bigger win is switching to a modern format. Newer formats store the same photo in far fewer bytes. The same 577 KB photo came out as:
| Format | File size | Change |
|---|---|---|
| Original JPEG | 577 KB | — |
| Compressed JPEG | 420 KB | −27% |
| HEIC | 249 KB | −57% |
| AVIF | 233 KB | −60% |
| WebP | 138 KB | −76% |
Use WebP or AVIF for websites, HEIC for keeping photos on Apple devices, and stick with JPEG when you need a file that opens absolutely everywhere.
Tips
- Resize before you compress. A full-size iPhone photo is far bigger than most screens need.
- Compress from the original. Re-compressing a JPEG again and again slowly adds blur and blockiness.
- Keep originals you care about. Compressed copies are perfect for sharing; keep the full-quality file for printing or editing.
Related guides
- How to reduce image file size on a Mac
- Convert JPG to WebP
- How to compress images for email
- How to convert HEIC to JPG on a Mac
FAQ
How do I reduce the size of a JPEG on a Mac?
Open it in Preview, choose File > Export and lower the Quality slider. For many photos at once, drag them into TinyPresso, which compresses them in a batch and can convert them to smaller formats like WebP or HEIC.
What is the smallest format for photos?
Modern formats like WebP, AVIF and HEIC are much smaller than JPEG. In our test a 577 KB JPEG became 138 KB as WebP, 233 KB as AVIF and 249 KB as HEIC.
TinyPresso compresses and converts images right on your Mac — free to use, 100% offline.
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