NET

21 Its alcoves, three on each side, and its jambs and porches had the same measurement as the first gate; 87½ feet long and 43¾ feet wide.

Darby

21 And its chambers were three on this side and three on that side; and its posts and its projections were according to the measure of the first gate: its length was fifty cubits, and breadth five and twenty cubits.

KJV

21 And the little chambers thereof [were] three on this side and three on that side; and the posts thereof and the arches thereof were after the measure of the first gate: the length thereof [was] fifty cubits, and the breadth five and twenty cubits.