But for those of you like me, with a lot more on our minds then which months have 31 or 30 days or even 27 or 28, here is an easy method for finding out which months have 31 days. Count your knuckles and the spaces between for each month. Start with your pinky knuckle on your left hand. That knuckle is January which has 31 days. The space next to that represents February which has less than 31 and so on with March being a knuckle having 31 days. The first knuckle on your right hand should be August which has 31 days and you would end with December on your right ring finger knuckle. Easy, right?