Save screenshots as JPEG on a Mac

For my blog I take a lot of screenshots. By default macOS stores them as PNG. If PNGs eat too much disk space for your taste, switch to JPEG.

Open Terminal and run:

defaults write com.apple.screencapture type JPG
killall SystemUIServer

Works the same for TIFF, GIF or PDF instead of JPG.

From now on, Shift-Command-3 or Shift-Command-4 saves screenshots in the selected format.

Note: JPEG has no transparency. You’ll notice it on screenshots of individual windows.