435. Accepted Conventions of Measuring

62:10 One should measure according to the accepted local practice and not “do his own thing.” For example, if the common practice is to measure in a heap, the shopkeeper should not level it, even if the customer prefers that he do so in order to lessen the price. Conversely, in a place where the practice is to level measures, one should not make a heap, even if the customer wants this and is willing to pay extra. The Torah takes false measures extremely seriously. Even in cases such as these, we are concerned that a bystander not observe the transaction and make mistaken assumptions about how measures are commonly taken in this locale. He might then go and measure improperly for his own customers and end up shorting them on their purchases.

62:11 The leaders of the community are obligated to appoint supervisors to monitor the shops. If they find that a merchant in their jurisdiction has faulty weights or measures, they are empowered to fine or otherwise penalize the offender in order to enforce compliance.