The phrase “a baker’s dozen” means 13 instead of the usual 12, and it has roots in medieval England.

At the time, strict laws regulated the weight and price of bread. The Assize of Bread and Ale set standards to prevent bakers from cheating customers by selling underweight loaves. Penalties for shortchanging customers could be severe, ranging from fines to flogging, and in extreme cases, even the loss of a hand.

To avoid punishment, bakers began adding an extra loaf when selling a dozen. This way, if one loaf was underweight, the customer still received fair value. The practice became so common that “a baker’s dozen” entered the language as a term for 13.

The phrase has been in use since at least the 16th century, a practical solution that left a lasting linguistic legacy.