Former Rosh Kollel (Warsaw, 2013-17)
Currently Head of the English department at Machon HaTorah Ve’Haaretz, the Institute for Torah and the Land of Israel

The Torah states (Devarim 14:23): “You shall consume the tithes of your new grain, wine, and oil…  in the place where He will choose to establish His name so that you may learn to revere the L-rd your G-d forever.”

Ma’aser sheni differs from all other types of ma’aserot, inasmuch as it isn’t given to a third party (Kohen, Levi, or a poor person). Rather, it goes to the produce’s owner and his family, who eat it in Jerusalem in a state of ritual purity. Ma’aser sheni is sacred.
In the times of the Beit HaMikdash, each person would bring up their produce to Jerusalem, eat it in ritual purity within the walls of Jerusalem, together with their families—similar to kodashim kalim.

The Torah makes provisions for those who live far away from the Beit HaMikdash: they can transfer the sanctity of their ma’aser sheni to money, bring the money to Jerusalem, and buy and eat food there in a state of purity.

Shmuel teaches (Temura 27b): “Consecrated property worth one hundred dinars [maneh] that one desacralized [transferred to a coin worth] one peruta is desacralized.” That is, bedi’aved one can transfer an object’s sanctity to money less than its actual value. Minimum value for this is equivalent to one peruta.
Today we can no longer eat ma’aser sheni since we are all tamei lamet and have neither a mizbe’ach or Beit HaMikdash. The money is also sacred and it cannot be used for any other purpose. For this reason, the Geonim write that today, lechatchilait’s possible to redeem ma’aser sheni on a shave peruta (based on Erchin 29b). Modern poskim rule accordingly.

How much is a peruta worth today?

As we mentioned, the sanctity of ma’aser sheni needs to be transferred to a coin worth at least a peruta. A peruta is a bronze coin that was the smallest coin of value in Mishnaic times. The value of a peruta is half a kernel of barley of sterling silver (Shulchan Aruch, YD §331, 134). The weight of a standard kernel of barley is 0.05 g, meaning a peruta is worth 0.025 g; that is, 1/40 g of sterling silver.
Today we don’t purchase silver by the gram or kilogram, rather by the ounce (Troy ounce, oz t, to be precise), which weighs 31.1035 g. That is, we need to take the price of an ounce of silver and divide it by 1244.14 (40 x 31.1035). It is generally calculated in dollars; in Israel, the amount needs to be converted to shekels.
Today (24 Av 5779), 1 oz t of silver is purchased at $16.93, or NIS 59.44. This means that a peruta is 4.77 agorot (59.44 ÷ 1244.14), or 1.36 cents (16.93 ÷ 1244.14). However, since one must pay VAT (17%) to purchase silver, we multiply this amount by 1.17. This brings us to 5.59 agorot or 1.59 cents.

The higher the price of an ounce of silver, the higher a peruta’s value. In the past (2011), 1 oz t of silver rose to a staggering $47, so the peruta’s value rose accordingly. In 2001, though, it plunged to $6.
In conclusion: 1 peruta = the price of 1 oz t of silver ÷ 1244.14 × 1.17.
1 peruta today (Av 5779, August 2019) – 1.6 cents or 5.6 agorot. 
In practice, we can use a 10 agorot coin or a nickel to avoid having to check each time.

Using a 10 Shekel coin

There is no problem using a coin of greater value for the long term. That is, if we take a 10 shekel coin, for instance, and we figure (for the sake of this example) that each transfer “takes up” 10 agorot in my coin, we can reuse the coin for another 99 transfers. However, we have to ensure that we do not use the coin beyond this limit. If used beyond the limit when there is no more room left in the coin for the sanctity, the ma’aser sheni sanctity remains in the produce. The transfer is then void and the produce is still sacred and forbidden to eat!
When the coin is filled to its capacity, there is a very practical solution: we can take another 10 agorot coin and transfer the sanctity of the original (NIS 10) coin onto the new peruta vareva in the 10 agorot. This new 10 agorot coin should be defaced or thrown into the sea. Now the old NIS 10 coin is freed up for another 100 transfers.

New service: Beit HaOtzar membership for tourists
Upon request, we added a new membership option: a one-time membership (for two months) to Beit HaOtzar, which includes a designated coin for ma’aser sheni handled on the member’s behalf, for only NIS 18. This service is meant primarily for tourists visiting Israel who want to separate terumot and ma’aserot in a mehudar fashion relying on the coin in Torah VeHa’aretz Institute’s safe. This two-month membership makes this possible without having to commit to the full year-long membership.
This option is available on our website under Our Services (check Tourist).