Ezekiel 43:16

The altar hearth shall be twelve [cubits] long by twelve broad, square in the four sides of it.

Exodus 27:1

"You shall make the altar of acacia wood, five cubits long, and five cubits broad; the altar shall be foursquare: and its height shall be three cubits.

Exodus 38:1-2

He made the altar of burnt offering of acacia wood. It was square. Its length was five cubits, its breadth was five cubits, and its height was three cubits.

2 Chronicles 4:1

Then he made an altar of brass, twenty cubits its length, and twenty cubits its breadth, and ten cubits its height.

Ezra 3:3

They set the altar on its base; for fear was on them because of the peoples of the countries: and they offered burnt offerings thereon to Yahweh, even burnt offerings morning and evening.

Treasury of Scripture Knowledge

Summary

And the altar shall be twelve cubits long, twelve broad, square in the four squares thereof.

Square

Bible References

Twelve cubits

Exodus 27:1
"You shall make the altar of acacia wood, five cubits long, and five cubits broad; the altar shall be foursquare: and its height shall be three cubits.
2 Chronicles 4:1
Then he made an altar of brass, twenty cubits its length, and twenty cubits its breadth, and ten cubits its height.
Ezra 3:3
They set the altar on its base; for fear was on them because of the peoples of the countries: and they offered burnt offerings thereon to Yahweh, even burnt offerings morning and evening.

Square

Exodus 38:1
He made the altar of burnt offering of acacia wood. It was square. Its length was five cubits, its breadth was five cubits, and its height was three cubits.