We have seen a user avatar will have different sizes on Facebook, Twitter, etc.
For example, Twitter has 3 different avatar sizes: 24×24, 48×48, 128×128; Facebook mainly has 50×50 and 180×180>.
I am wondering if there is a standard thumbnail size that a website should adopt, or it’s all solely based on the design?
Thanks.
Like you say its just down to the design of your site. If in doubt, adopt the same resolution as a big player like Twitter, and allow users to upload a larger image which will give you the flexibility to show a larger version if someone clicks through to their profile.