What Is Meant by a Baker’s Dozen and Where Did This Expression Come From?
A baker’s dozen is 13 (or, more rarely, 14), instead of 12. A baker’s dozen takes on importance in large families, where that little extra goes a long way. It’s widely believed that this expression originated from the practice of medieval English bakers giving an extra loaf when selling a dozen in order to avoid being penalized for selling short weight.
Even with careful planning it is difficult to ensure that all of your baked goods come out the same size; there may be fluctuations in rising and baking and air content, and many of these bakers didn’t even have scales to weigh their dough.
For fear of accidentally coming up short, they would throw in a bit extra to ensure that they wouldn’t end up with a surprise flogging later. In fact, during good harvests bakers added one excess loaf to middlemen. This addition was called the ‘in-bread’ or ‘vantage loaf’. When selling in quantity to middlemen or wholesalers they would add an extra loaf or two. When selling single loaves to individuals they would offer a small extra piece of bread.