How much is redemption of the firstborn
Question
How much money to I have to give the Cohen to redeem my firstborn son? How much is it in NIS?
Answer
Dear …!
First of all, I want to congratulate you and wish you a mazal tov on the birth of your firstborn son! May you merit to bring him up for Torah, marriage and good deeds. I also want to congratulate you with being presented with an opportunity to fulfill such a rear commandment that not everyone merits to perform.
It’s customary to give a Cohen coins of pure silver, whose total weight is 100 grams. The price of silver is determined by its current market value, plus a regular commission that is normally paid to a dealer.
You can always find out what the current halachic value of silver is (so that you can know what it is on the day of the redemption) by calling the information hotline of the Beis Medrash li-Hisyashvus ke-Halachah (an institute for studying the proper ways of keeping the commandments while settling the Land of Israel). The number is 02-6488888.
It’s recommended to pay the Cohen in actual silver coins, and not their equivalent. You can often purchase these coins from the Cohen himself, if he often participates in redemptions of the firstborn. Alternatively, you can buy them in a Judaica store.
Source
Shulchan Oruch, section Yore Deah, chapter 305, §1