The entire length of the structure was about 45 ft. in the clear, and its width about 15 ft.
The south side southward - Or, the south side on the right. As the entrance of the tabernacle was at its east end, the south side, to a person entering it, would be on the left hand: but we learn from Josephus that it was usual, in speaking of the temple, to identify the south with the right hand and the north with the left hand, the entrance being regarded as the face of the structure and the west end as its back.

And thou shalt make the boards for the tabernacle,.... As in the manner before described, so in number as follows:
twenty boards on the south side southward; which being a cubit and a half broad, made the length of the tabernacle fifteen yards according to the common account; but if these were cubits of twenty one inches, then its length was much greater.

Twenty of these boards were to be prepared for the side of the dwelling that was turned towards the south, and forty sockets (אדנים foundations, Job 38:6) or bases for the pegs, i.e., to put the pegs of the boards into, that the boards might stand upright; and the same number of boards and sockets for the north side. תּימנה, "southward," is added to נגבּה לפאת in Exodus 26:18, to give a clearer definition of negeb, which primarily means the dry, and then the country to the south; an evident proof that at that time negeb was not established as a geographical term for the south, and therefore that it was not written here by a Palestinian, as Knobel supposes, but by Moses in the desert.
The form of the "sockets" is not explained, and even in Exodus 38:27, in the summing up of the gifts presented for the work, it is merely stated that a talent of silver (about 93 lb.) was applied to every socket.