Understand what affects image file size
Four things drive an image's file size: its pixel dimensions, its format, its quality setting, and how much metadata is embedded in it.
Image Converter for Mac
Pixels guide
How to compress images on Mac
A short guide to what actually changes an image's file size, and how to compress one image or a whole batch with Macprit Pixels.
Pixels does not promise lossless compressionChoose a supported output format
JPG suits photos well, PNG suits images that need transparency, and WebP or AVIF can produce smaller files than either at a similar visual quality.
Set the quality and file-size target
Lower quality settings produce smaller files at the cost of some visual detail. Pixels does not promise lossless compression: reducing file size on a lossy format always trades away some quality.
Resize when the original dimensions are larger than needed
If the image is larger than the size you actually need, resizing it down before exporting reduces file size further, on top of format and quality choices.
Apply the same options to one image or a batch
Compress a single image, or add a folder of images and apply the same format, quality, and resize settings to all of them at once.
Decide whether to remove metadata
Photos often carry embedded metadata such as camera settings or location. Removing it trims a small amount of extra file size and avoids sharing that information along with the image.
Check the saved result
Compare the exported file's size and appearance against the original before you rely on it, since the right settings vary from one image to the next.
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