Weeeell, there are a few ways you can measure it. One way is to print screen your full signature to Paint and it'll measure the pixels for you. Another is basically to just eyeball it. There should be a post at the bottom of the rules thread that shows you about how big a signature can be. We're pretty lenient on it, so if you go over by like 10 or 20 pixels, it's alright. Just so long as it's not gargantuan.