Traditionally, a baker’s dozen is equivalent to 13, in some cases, 14. The reason behind the strange number is that, it is believed that in medieval times. bakers usually gave an extra loaf when selling a dozen to avoid being penalized for selling short weight. Others say that bakers usually baked 13 loaves instead of just 12 – to make sure they have an extra piece, just in case one loaf isn’t cooked well.