How to compress screenshots on a Mac

A single Mac screenshot can easily be close to a megabyte. That's because macOS saves screenshots as PNG at full Retina resolution — twice the width and height of what you see on screen. Here's how to make them much smaller without making text blurry.

Why Mac screenshots are so large

• Retina resolution. On a Retina display, a screenshot has 4× the pixels of the same area on an older screen.
• PNG format. PNG keeps every pixel perfect, which is great for sharp text — and heavy on file size.

1. Change the screenshot format (not always a win)

You can tell macOS to save screenshots as JPEG instead of PNG by running this in Terminal:

defaults write com.apple.screencapture type jpg

To switch back, run the same command with png. But be careful: JPEG can make text and sharp edges look fuzzy, and it isn't always smaller. In our test, a 2880×1800 screenshot saved as JPEG was 391 KB — bigger than the same screenshot compressed as PNG (261 KB).

2. Resize it in Preview

If the screenshot will be shown small — in a doc, a ticket, an email — open it in Preview and choose Tools → Adjust Size…. Halving the width and height leaves a quarter of the pixels, and fewer pixels means a smaller file. Just don't shrink it so much the text becomes unreadable.

3. Compress it with TinyPresso (the big win)

Screenshots are full of flat colors and repeated shades, which makes them ideal for smart compression: remove the color detail your eyes can't tell apart and the file shrinks dramatically while text stays perfectly crisp. In our test, a 2880×1800 Retina screenshot went from 875 KB to 261 KB (−70%) as a PNG, in about two seconds.

Need it even smaller for a website? Choose WebP as the output format — the same screenshot came out at 94 KB (−89%).

The fastest workflow

1. Press ⌃⇧⌘4 to capture an area straight to the clipboard.
2. Switch to TinyPresso and press ⌘V.
3. A compressed copy lands in your export folder. Right-click the row and choose Copy to paste it anywhere.

Got a backlog? Select all your screenshots in Finder and drag them in at once — TinyPresso compresses the whole batch, and can move the originals to the Trash for you (they stay recoverable).

Related guides

• How to compress PNG files on a Mac
• Compressing images for the web
• Convert PNG to WebP

FAQ

Why are Mac screenshots so big?

macOS saves screenshots as PNG at full Retina resolution, which has four times the pixels of a standard display. PNG keeps every pixel perfect, so the files get large.

Should I save Mac screenshots as JPEG to make them smaller?

Not always. JPEG can make text look fuzzy, and in our test a JPEG screenshot (391 KB) was bigger than the same screenshot compressed as PNG with TinyPresso (261 KB).

How do I make a screenshot smaller on a Mac without losing quality?

Compress it with an app that removes only detail you can't see, such as TinyPresso. A 875 KB Retina screenshot dropped to 261 KB in our test while text stayed crisp.