A mathematician just came up with the formula for the perfect snowman. 

If you're good at eye-balling (see what I did there?) then you won't need to break out the ruler.  If not, maybe you should, if you don't want it to be all deformed.  From The Daily Mail:

1.  It should be 64 inches tall, or a little over five feet.  The bottom ball should be 31 inches high, the middle ball should be 20 inches, and the head should be 13 inches.

2.  Use fresh snow that fell when it was 32 degrees or colder outside.

3.  The eyes should be no more than two inches apart.

4.  The carrot nose should be 1.5 inches.

5.  You can use sticks for arms, plus any hat and scarf.  Just make sure the three buttons on the chest are an equal distance apart.