How many is a baker's dozen?

A baker's dozen, devil's dozen, long dozen, or long measure is 13, one more than a standard dozen. The broadest use of baker's dozen today is simply a group of thirteen objects (often baked goods). The term has meant different things over the last few centuries.

In the United Kingdom when selling certain goods, bakers were obliged to sell goods by the dozen at a specific weight or quality (or a specific average weight). During this time, bakers who sold a dozen units that failed to meet this requirement could be penalized with a fine. Therefore to avoid risking this penalty, some bakers included an extra unit to be sure the minimum weight was met, bringing the total to 13 units or what is now commonly known as a baker's dozen.

According to the Oxford English Dictionary, the term "baker's dozen" originated in the late 16th century and is "apparently so called after the former practice among bakers of including a thirteenth loaf when selling a dozen to a retailer, the extra loaf representing the retailer's profit."

According to the 1811 Classical Dictionary of the Vulgar Tongue, by Francis Grose, "a Baker's Dozen is Thirteen; that number of rolls being allowed to the purchaser of a dozen". However, contrary to most sources, according to the anonymous 1785 version of that dictionary, which was probably also by Grose, "a Baker's Dozen is Fourteen, that number of rolls being allowed to the purchaser of a dozen".