what is the halacha of overcharging? the rule everyone quotes is a sixth (onaah). where does that number come from, what happens in each case, and does it still apply today when there is no single market price?
the source is a pasuk: וכי תמכרו ממכר לעמיתך או קנוה מיד עמיתך אל תונו איש את אחיו (ויקרא כה יד). overcharging or underpaying is a real לא תעשה, not just a pricing dispute (rambam, hilchos mechirah 12:1).
the mishnah (bava metzia 4:7) sets the line: האונאה ארבעה כסף מעשרים וארבעה כסף לסלע שתות למקח, one sixth of the value. the rambam and shulchan aruch (choshen mishpat 227) split it into three cases: more than a sixth, the deal is void. exactly a sixth, the deal stands but the extra money goes back. less than a sixth, the deal stands and nothing goes back, because people wave off small differences.
and the window to complain is short: only until the buyer has had time to show the item to a merchant or a relative and learn the real price. after that, even a sale at double the value cannot be undone (rambam mechirah 12:5, mishnah 4:7).
one more wrinkle: choshen mishpat 227:27 says if the seller openly states what the item cost and what the markup is, there is no onaah at all.
so the question today: the sixth assumes a going price that people can be wrong about. in normal retail every store sets its own price and margins vary wildly. in dropshipping the seller barely touches the product and prices float everywhere. is there still a measurable market price that the sixth is measured against? and if a seller openly tells the buyer the markup, does 227:27 take the sale out of onaah completely?
Thank you Rabbi, thank you very much.
The laws of ona’ah are real Halachah, but the classic one-sixth calculation is much less relevant to ordinary retail today because there often is no single fixed market price.
Today a buyer can usually compare dozens of sellers within seconds. One store charges $50, another $70, another $90, and the buyer understands that each seller has his own markup, service, convenience, return policy, location, and business model. If he knowingly chooses to pay $90, it is difficult to call that classic ona’ah merely because somebody else sells it for less.
Choshen Mishpat 227:27 says that if the seller says, חפץ זה בכך וכך לקחתיו כך וכך אני משתכר בו, “I paid this amount and this is my profit,” there is no ona’ah. Literally that case involves disclosure of the actual markup, but the concept is very relevant today: the buyer generally understands that the seller is making a profit, can investigate the market himself, and nevertheless chooses to buy at that price.
So I would not calculate sixths every time Amazon, Walmart, a local store, and a dropshipper charge different prices for the same product.
Where these halachot may become much more relevant is when there is no real market choice, such as a monopoly controlling something necessary and charging outrageous prices. (Like Pharmaceutical Companies) Then there can be serious halachic problems, although the exact category may sometimes be הפקעת שערים rather than ordinary ona’ah.
The basic question today is usually not, “Is this price one-sixth higher?” It is: was the buyer deceived or trapped, or did he knowingly choose to pay the advertised price in an open market?