what shape is a stop sign

A stop sign is an octagonal (eight-sided) shape. It is the only road sign with this shape, which makes it easy to recognize it by both shape and color. The sign is red with white lettering, and it says "STOP" in either English or the national language of the country where it is located. In the United States, stop signs are 30 inches (76 cm) across opposite flats of the red octagon, with a 3/4-inch (2 cm) white border. The white uppercase stop legend is 10 inches (25 cm) tall. The Vienna Convention on Road Signs and Signals also allows an alternative version: a red circle with a red inverted triangle with either a white or yellow background, and a black or dark blue STOP.