How to resize and compress images on Mac

Width, format and quality, by drag and drop

The simplest method: SeventyPix

Install SeventyPix, drop your images into the window, pick the maximum width (640 to 2560 px, or original size), the output format (JPG, PNG, HEIC, WebP if your Mac offers it) and the quality (slider from 50 to 100%, 80% by default). Click "Convert": each image comes back lighter right next to the original, with a suffix, never touching the source file. The size saved shows up immediately.

Download the free SeventyPix trial (7 days, macOS 13+).

Why resize or compress an image

Lighter attachments: a photo taken with a recent iPhone often weighs 3 to 4 MB or more, and many messaging apps and forms cap well below that.
A faster website: lighter images mean pages that load faster, a factor search engines increasingly take into account.
Less storage used: on your Mac, on a USB drive, or in cloud storage billed by volume.

Which format to pick: JPG, PNG, HEIC or WebP

JPG remains the most universal choice for photos. PNG suits images with transparency or crisp screenshots. HEIC, the iPhone's default format, weighs roughly half as much as a JPG at comparable quality but opens less smoothly outside the Apple ecosystem. WebP often offers the best size-to-quality ratio for the web; SeventyPix only offers this option if your macOS can encode it on your machine.

Stripping GPS and EXIF data before sending a photo

A photo taken with a smartphone often contains, besides the date and device model, the exact GPS position where it was shot. SeventyPix can strip this metadata automatically (checkbox on by default) at conversion time, a useful habit before sending an image to someone or publishing it online.

Mistakes to avoid

Compressing too aggressively without checking the result: past a certain point, artifacts become visible, especially on flat color areas.
Sending photos at full original size and quality by reflex, when a 1920 px width is usually plenty for on-screen use.
Forgetting to strip GPS metadata before sharing a photo taken somewhere sensitive (home, workplace).

Get SeventyPix: 7-day trial, then a lifetime license.