Baker's Dozen
Modern equivalent
13 units
The classic British protective buffer (12+1) used by medieval tradesmen to guarantee compliance with royal market laws.
Under strict laws like the 1266 Assize of Bread and Ale, bakers who short-changed customers on the weight of their loaves faced severe public penalties, fines, or corporal punishment. To prevent accidental under-weight batches caused by variable flour moisture and oven conditions, bakers routinely added a thirteenth loaf for free—known traditionally as the "baker's dozen" (or "vantage loaf").