Berean Standard Bible (BSB)
It was square when folded over double, a span long and a span wide.
World English Bible (WEB)
It was square. They made the breastplate double. Its length was a span, and its breadth a span, being double.
Strong's King James
It was foursquare{H7251}{(H8803)}; they made{H6213}{(H8804)} the breastplate{H2833} double{H3717}{(H8803)}: a span{H2239} was the length{H753} thereof, and a span{H2239} the breadth{H7341} thereof, being doubled{H3717}{(H8803)}.
The F.O.G *
The F.O.G Message *
Young's Literal Translation
it hath been square; double they have made the breastplate, a span its length, and a span its breadth, doubled.