How to compress images and convert formats on a Mac
You do not need a large app to shrink a picture on a Mac. Two built-in routes cover single files; batches and stronger compression are where a dedicated tool earns its place.
Using Preview
Open the image, then File › Export to pick a format (JPEG, PNG, HEIF, TIFF) and drag the quality slider; Tools › Adjust Size changes dimensions. Preview can export a selection in bulk too, with fewer options.
Using Shortcuts
Shortcuts includes Convert Image and Resize Image actions. Chain them, save as a Quick Action, and you can run it from the context menu. Good for one setup you reuse; tedious once every parameter combination needs its own shortcut.
Straight from the right-click menu
Rightora puts these actions directly in Finder's context menu: compress, resize (presets such as 50% or 1920px wide, or your own), convert format (JPEG, PNG, HEIC, TIFF, AVIF, WebP), quick crop, remove background and upscale. Select a batch and the same action runs across all of it, with a cancellable progress panel and a failure report.
Beyond the system frameworks you can install professional processing components such as pngquant and MozJPEG, which reach smaller files at the same visible quality. They install in one click from inside the app, with no command-line setup.
Which format to pick
- JPEG: photos and anything you need to send around; the safest compatibility.
- PNG: screenshots and anything needing transparency; lossless but larger.
- HEIC: smaller than JPEG at the same quality and fine inside the Apple ecosystem; convert back to JPEG before sending to Windows users.
- WebP: for the web, usually smaller than both JPEG and PNG at the same quality.
FAQ
Does compressing an image on a Mac lose quality?
JPEG, HEIC and WebP are lossy, so there is always some loss. A good compressor simply gets further down in size before the difference becomes visible. Use PNG or lossless WebP when you need none at all.
How do I compress a whole folder of images at once?
Select the images and right-click; Rightora runs the same action across all of them with progress and a failure report. Batch processing is a Pro feature.
Can a Mac export WebP directly?
Not through the built-in export options. Once the matching processing component is installed, WebP appears in Rightora's Convert Format submenu.
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