One complaint I hear over and over again is how boring and dull WordPress commenting system looks. The avatars are nice, but they are so small. In fact, in the twentytwelve theme, comment avatars are 44 pixels by 44 pixels.
Unfortunately, WordPress doesn’t give us an option in the admin to change the size of the avatar (side note here – it would be cool if this is something they added in WordPress 3.6 with the twentythirteen theme). Believe it or not, the avatar size is actually hard-coded to a 44 pixel square.
Fortunately, there is a way to change the size of the avatar, if you are willing (and able) to make modifications to your themes
If you are using the twentytwelve theme, or a theme derived from it, the code we are interested in should be on line 288.
All you have to do is change the ’44’ to whatever you want the size of your avatar to be. For this site, I chose 96, and I think it’s a good fit with my theme and the style of my comments. Different sizes might work better for you.