Albert Barnes Commentary 1 Kings 6:2

"And the house which king Solomon built for Jehovah, the length thereof was threescore cubits, and the breadth thereof twenty [cubits], and the height thereof thirty cubits." — 1 Kings 6:2 (ASV)

The size of Solomon’s temple depends on the true length of the ancient cubit, which is doubtful. It has been estimated as somewhat less than a foot, and again as between 19 and 20 inches—a difference of nearly 8 inches, which would produce a variation of nearly 40 feet in the length of the temple chamber and 46 feet in the length of the entire building. It is worthy of remark that, even according to the highest estimate, Solomon’s temple was a small building, less than 120 feet long and less than 35 feet wide.

It is also remarkable that the measures of the temple, for both the “house” and the porch (1 Kings 6:3), were exactly double those of the older tabernacle (Exodus 26:18). This identity of proportion amounts to an undesigned coincidence, indicating the thoroughly historical character of both Kings and Exodus.