Mac storage basics · Creative and media apps

How do I make an image file smaller using Preview?

Short answer: In Preview use Tools → Adjust Size to cut the pixel dimensions, or File → Export as JPEG/HEIC with a lower Quality setting. Save a copy to keep the original.

Open the image in Preview, then:

  • Tools → Adjust Size… to reduce the pixel dimensions (big photos rarely need to be full size for sharing).
  • File → Export…, choose JPEG or HEIC, and drag the Quality slider lower; the estimated file size updates as you go.

Save under a new name if you want to keep the original. For a batch, select several images in Finder, open them together in Preview, select all thumbnails in the sidebar and use Adjust Size once. For video, see making a video file smaller.

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