How do you set the image for your UIBarButtonItem
?
I believe if you use this method you should have no problems:
UIBarButtonItem *homeBarButtonItem = [[UIBarButtonItem alloc] initWithImage:yourImage style:UIBarButtonItemStylePlain target:self action:@selector(yourSelector:)];
This way you do not have to worry about sizes. Just make sure that you have retina version of the image. (you should have "home-25.png"-25x25 pixels image for non-retina devices (if necessary) and "home-25@2x.png"-50x50 pixels image for retina devices.