The Google Play app icon size
Google Play needs a 512 x 512 pixel app icon for the store listing, as a 32-bit PNG (transparency allowed) of at most 1024 KB. Google Play applies its own corner rounding and shadow.
How to make a good Google Play app icon
Upload a full square and let Google Play round it. Keep the main shape inside the central area so the mask never cuts into it.
Questions
What size is a Google Play app icon?
Google Play needs a 512 x 512 pixel app icon for the store listing, as a 32-bit PNG (transparency allowed) of at most 1024 KB.
Can a Google Play icon have transparency?
Yes, the icon is a 32-bit PNG, so an alpha channel is allowed.
Is my image uploaded anywhere?
No. The image is read and resized in your browser; nothing is sent to a server.
How does the resize work?
It scales the image to cover the target size and crops the overflow evenly from the edges, so nothing is stretched.