Screenshot sizes for publishing android app on Google Play

• We require 2 screenshots.
• Use: Displayed on the details page for your application in Google Play.
• You may upload up to 8 screenshots each for phone, 7” tablet and 10” tablet.
• Specs: Minimum dimension: 320 pixels. Maximum dimension: 3840 pixels. The maximum dimension of your screenshot cannot be more than twice as long as the minimum dimension. You may use 24 bit PNG or JPEG image (no alpha). Full bleed, no border in art.
• We recommend adding screenshots of your app running on a 7" and 10" tablet. Go to ‘Store listing’ page in your Developer Console to add tablet apps screenshots.

https://support.google.com/googleplay/android-developer/answer/1078870?hl=en&ref_topic=2897459

When I publish apps I use the following screenshot sizes:

Phone: 1080 x 1920 I prepare 8 images with title, some fancy background and a screenshot inside a smartphone mockup. So it's more than a simple screenshot. It gives some nice branding and helps you to stand out from other apps out there.

Tablet 7": 1200 x 1920 - I do actually a couple of raw screenshots of 7" emulator so that the user could know how the layout will appear on his device. No fancy design with titles etc.

Tablet 10": 1800 x 2560 - same thing here, just a couple of raw screenshots.

all in .png format. Hope this helps.

It has to be any one of the given sizes and a minimum of 2 but up to 8 screenshots are accepted in Google Playstore.