A fifth part - Better than the margin. The meaning seems to be that the lintel was one-fifth of the width of the wall, and each door-post one-fifth of its height. Thus the opening was a square of four cubits, or of six feet.
Related Commentaries of 1 Kings 6:31
1 Kings 6:31
31 And for the entering of the oracle he made doors of olive tree: the lintel and side posts were a fifth part of the wall.