Parshat Behukotai. The buying power of Biblical Shekel.
It is well known that the buying power of a shekel in the times of Hazal was much greater than today. In this essay we will try to show that the buying power of silver in Biblical times was even much greater than in the times of Hazal. We will also try to analyze the prices and salaries in various times and finally offer some Hidushim in regards to the laws of Erechin described in our Parsha.
In the time of the Talmud, a skilled worker used to make close to one Biblical shekel a day which today would be equivalent to $10, but the buying power of this Shekel in terms of bread or other foods was much larger than $10. In fact they could buy close to as much food as today on one day’s salary. In the times of Hazal one could go to judgement over a dispute of a pruta (a coin worth 1/192 of a dinar). If we consider a dinar according to today’s prices of silver to be about $2.50, a pruta is slightly more than a cent. A pruta was also sufficient to perform the mitzvah of Kidushin. One could buy some fruits for a pruta. It’s reasonable to assume based on average salaries and food prices that while in terms of prices of silver, a pruta is a little more than a cent, in terms of buying power it was closer to a quarter today. We can thus say that the buying power of silver went down about 20 times in the last 1500-2000 years.
Now when we consider the buying power of silver during Biblical times, it seems it was another 20 or more times greater than in the times of Hazal. Yosef was sold for 20 shekels. The Torah says that the owner of a bull that killed a slave has to pay 30 shekels. Our Parsha determines that a field of 75000 square amot (about 200,000 square feet) for 49 years was redeemed at 50 shekels.
Another topic our Parsha explains in detail is donating one’s “Erech” (value) to the Temple. The “Erech” depended only on one’s age and gender. The largest “Erech” was of a grown up man: 50 Biblical shekels. Donating one’s “Erech” to the Temple was probably a simple way to donate one’s value without having to do complex estimations. It’s hard to know today when one would do this procedure, but it’s possible it was done when a person simply wanted to show appreciation to Hashem’s gift of life, or maybe if he was saved from danger. Sometimes one would donate an “Erech” of someone else; presumably this was usually done for a loved one. A wealthy person who did not have children for a long time might give an “Erech” of a child. A rich mother whose son came back alive from war might donate his value to the Temple.
The “Erech” on an adult is consistent with slave prices in Torah but is totally inconsistent with prices silver in the times of Hazal and is certainly not consistent with prices of silver today. However if we assume that the buying power of silver became 20 times smaller between the Biblical period and Hazal and then again 20 times smaller between Hazal and our time, then all the prices seem reasonable. If a skilled worker in the times of Hazal made close to a shekel a day, then in Biblical times he would be making about a Biblical shekel a month. The “Erech” of an adult was then about equal to the salary skilled worker for 5 years. The price of a slave (if we assume it was about 30 shekels) was equal to about 3 years work of a skilled worker which seems too little at first, but given that slave work was not skilled and the slave also had to be fed, this is not unreasonably cheap.
Another interesting consequence of our assumption is the laws of rape. The Torah tells us the penalty for rape among others is a payment of 50 shekels. In times of Hazal this was only 2 month’s salary, and today it’s a salary of 2-3 days which does not seem like enough to serve as prevention. Indeed Hazal teach us that other penalties were paid and that the 50 shekalim is only the one fixed “knas” (penalty). It could be however that in Biblical times 50 shekalim – the amount of money a skilled worker can earn in 5 years of work (equivalent to almost half a million dollars today) was more than enough compensation to prevent rape.
Conclusion: it seems when we deal with times of Hazal when sums of money is mentioned, if we want to consider what this is equivalent to (not in terms of practical Halacha, but in terms of understanding the life of the society of the time) instead of converting the money in silver equivalent, we should multiply everything by about 20. If we want to consider Biblical times, we need to multiply by about 4000.
 Baba Metzia 76a. Biblical shekel was equal to two coins called shekel in the Talmud (for the reason see Ramban, Shemot 30:13) and to 4 coins called dinar or zuz. The approximate weight of Biblical shekel is debated but we will assume it was about 15 grams or half an ounce.
 Eiruvin 82b: 4 seah of bread would cost a Biblical Shekel. Assuming a seah to be about 7 liters, (close to 2 gallons), a loaf of bread that weights about a pound would cost 1/64 of a day’s salary, which may be equivalent of $2 today.
 Some of the things one could buy for about a pruta were: a few dates, a black marble stone, a bundle of tow cotton, mat of myrtle twigs (see Kidushin 12). See also SM”A on Choshen Mishpat 88:2.
 Sefer Melachim tells us that King Omri bought enough space to build Shmoron for just 6000 shekels.
 As the Erech of an adult man is about equal to his two month’s salary.
 While the factor of 20 seems reasonable in terms of people’s salaries versus the value of silver, there does remain a difficulty with the fact that the Torah requires one who misused Temple property to bring a Ram of two shekalim. If as I am assuming here one could earn only one shekel per month, such a ram would cost two monthly salaries which seems almost impossible (although a bull could reasonably cost that much). The truth is the Talmud (Kritot 27a) asks what to do when the rams are sold cheaper than 2 shekels and seems to conclude that there is no way to bring this korban (unless the prices go back up, see Rambam, Psuley Mukdashim 4:23).
 Interestingly, according to this, the half a shekel per year donation to the Temple, in Biblical times meant 1/20 of one’s salary, and probably in case of not skilled workers, was close to maser kesafim – 1/10 of one’s salary.
 This is consistent with what we know about the slaves in Rome: their cost would often be equivalent to a thousand Biblical shekels, which is the salary for 3 years of work of a skilled worker.
 We also have to take into account that people did not live as long as today and when buying a slave one risked that he/she would get sick and die within just a few years.