Q: #375. What is a cubit?
By: Steve Shirley
A: The word "cubit" comes from the Latin word "cubitum" (Hebrew: "ammah") meaning "elbow." The word "cubit" is used 263 times in the Bible, with all but 4 uses in the Old Testament. A cubit was a unit of measurement which was very imprecise. Technically, it was the distance from the elbow to the end of the middle finger. Obviously then, since this distance varied from person to person, we can see why it was imprecise.
However, it appears that a cubit basically fell between lengths of about 18" to 21." The Bible appears to primarily use the smaller size, while other cultures used the larger sizes. Apparently, archaeologists have discovered a number of rods from different cultures which were used to measure a cubit, and these average around 20.6." Smith's Bible Dictionary lists three cubit lengths, and gives them these names: "The cubit of a man or the common cubit (see: Deut 3:11)," "The old Mosaic or legal cubit," and "The new cubit." The larger cubit size appears to be mentioned in (Ezek 40:5), which says "in the man's hand was a measuring rod of six cubits, each of which was a cubit and a handbreadth (app. 3")." This would make the cubit described as 21" (18" + 3").
The first time this unit of measurement is used in the Bible is in describing Noah's Ark. It was 300 cubits long, 50 cubits wide, and 30 cubits high (Gen 6:15). Most modern translations (i.e. NIV & NLT) today convert this to 450' long, 75' wide, and 45' high. This correlates to a cubit being 18." In (1 Sam 17:4), Goliath's height is said to have been "six cubits and a span." A "span" was the distance between the tip of the thumb and and little finger with the hand fully open, generally about 9 inches (or half a cubit). This would have made Goliath about 9'9" tall.