I'm currently designing a social oriented app that has a feed. To the left of every message would be the avatar of the user. I know that it depends from project to project but nonetheless what seems to be the pattern in size that designers have set on average?
2 Answers
It is different case by case and it depands on the location and the importance of the avatar in the specific situation.
The highest importance is probably in the user profile screens. In this detail screens, users expect larger and more detailed picture. Can be higher than 120-180px.
Another good place to use big avatar is list app (contacts or messaging apps) because the avatar is used as Guidance element. For example skype is about 80px, Facebook messenger about 120px.
Third option is the place where the avatar is actualy not very important. It can be inside the conversation thread or in the social app feed. In these cases the most important thing is the content so that the avatar is quite small (about 60px for FB, Skype and Instagram).
// The px sizes are from iOS apps and only tentative!
In addition to prev answer by Michal can add that size of avatar may depends also on main related social network.
For example if your app be oriented to work with FB or use social login by FB then better to use FB size of avatars, etc.
More information about social media sizes you can take there ( 2014 Social Media Image Sizes: A User’s Guide for Graphic Designers) and there ( Facebook, Twitter, Pinterest, Instagram – Social Media Image Size Cheat Sheet [INFOGRAPHIC] )