Minhag Hamedinah
Common Commercial Practice #20
Measures
Q. Does it make a difference whether I sell items in feet or meters, pounds or kilos, liters or gallons?
A: The Mishnah (B.B. 88b) teaches that in places where it is common to sell in a large measure, a person should not sell in a small measure, and vice-versa, even if the price is adjusted accordingly (C.M. 231:8).
This is for two reasons: 1. Typically, the seller adds a drop “extra” to each measure, since it is not possible to measure exactly. Therefore, by using a larger measure than customary, there are less “extras” than expected; a smaller measure, more “extras” than expected (Sma 231:13).
2. People may mistakenly think that this measure is standard also when buying from others, and miscalculate the price. For example, a person may not notice the difference between a quart and a liter, or between a meter and a yard, when comparing the prices (Sma 231:14).
Therefore, you should sell using the measures that are standard and the common practice in that location.
