App Store screenshot checker
Drop your images and check them against the sizes Apple accepts for Mac apps. Your files stay in your browser.
The sizes Apple accepts
For Mac apps Apple accepts 1280 x 800, 1440 x 900, 2560 x 1600 and 2880 x 1800 pixels, all 16:10. Files can be .jpeg, .jpg or .png, can't include alpha channels or transparency, and you need between 1 and 10 per device size.
Source: App Store Connect Help, Screenshot specifications, checked October 30, 2026. Apple can change these, so its page wins if the two ever differ.
Removing an alpha channel
In Preview, choose File, Export and untick Alpha. In Terminal:
sips -s format jpeg shot.png --out shot.jpg