Resolution of Unity 3d GUI button

Hi everyone, I’m trying to make a GUI button and I would like to know does anyone know what the resolution of Unity 3d’s original GUI button is? I think it’s smaller than 25x25 because I tried to make a button in that resolution and the font that I was using didn’t show up.

There is no set resolution. It’s a 9-slice system and you set the borders and so on in the GUI style.