Jezekiel 43:16

16 And the altar of the length of twelve cubits, by twelve cubits , square upon its four sides.

Jezekiel 43:16 In-Context

14 from the bottom at the commencement of the hollow part to this great mercy-seat, from beneath was two cubits, and the breadth was a cubit; and from the little mercy-seat to the great mercy-seat, four cubits, and the breadth was a cubit.
15 And the altar four cubits; and from the altar and above the horns a cubit.
16 And the altar of the length of twelve cubits, by twelve cubits , square upon its four sides.
17 And the mercy-seat fourteen cubits in length, by fourteen cubits in breadth on its four sides; and a border to it carried round about it of half a cubit; and the rim of it a cubit round about; and the steps thereof looking eastward.
18 And he said to me, Son of man, thus saith the Lord God of Israel; These are the ordinances of the altar in the day of its being made, to offer upon it whole-burnt-offerings, and to pour blood upon it.

The Brenton translation of the Septuagint is in the public domain.