Square footage is a measurement of area. That area can be any shape, rectangle, triangle, circle, oval, just to name a few of many . Or if you're painting a 8 ft high wall, you can paint 37 1/2 feet in length. If you're painting a square, each side would be slightly over 17 ft.

300 feet if it is one foot wide.

There won't be any sides if you paint a big circle.