When you’re designing cover photos, graphics, and other social media assets, sometimes knowing the bare bones image dimensions isn’t enough. Here is everything you’ll need to know when creting images for your Google+ page.
Original Source: https://makeawebsitehub.com/social-media-image-sizes-cheat-sheet/
Google+ Image Sizes
Profile image: 250 px wide by 250 px tall
Cover image: 1080 px wide by 608 px tall
Shared image (on home stream): 497 px wide by 373 px tall
Shared image (on feed or your page): 150 px wide by 150 px tall