Also called Thirty pieces of silver, Shekels of silver.
The famous phrase with no unit in it — the Hebrew says only "thirty of silver", and leaves you to know it means shekels.
Mass
330–345 g (11.6–12.2 oz).
Defined as 30 shekels.
Reckoned from thirty shekels, the sum Exodus sets.
In Hebrew the phrase is simply a number and the word for silver: "thirty of silver". No unit is stated, because none had to be — a weight of silver meant shekels, the way a price in pounds needs no further explanation. So thirty pieces of silver is thirty shekels, and Exodus fixes exactly what that sum was for: the compensation owed when an ox gored someone else's slave. That is the price Zechariah is told to throw to the potter, and the price Matthew sees paid again.
Silver was weighed, not counted, until coins reached Judah, so each weight is drawn as the cube that much silver makes. A shekel is about a centimetre across; the thirty pieces of silver would sit in a palm; a talent is a block a hand and a half wide.
Not a word scripture uses. No unit appears in the Hebrew. "Thirty pieces of silver" is a translator's supplement for "thirty of silver", and shekels is the near-universal reading because silver was reckoned by weight in shekels.
Where it appears
Exodus 21:32Thirty shekels, for a slave gored by an ox