300 square feet. To calculate square feet simply multiply length by width - the result is the area in square feet.
15 times 20 equals 300 square feet. Isn't there a "calculator app" in your phone for this?
If you're talking floor tiles as opposed to wall tiles and by 12x12 you mean they are 12 inches square, then the answer is 300. Because each tile is one square foot and a 15'x20' room is 300 square feet. Simple, eh?
15' x 15' (225 square feet) = 25 square yards.
15 feet x 15 feet = 225 square feet.
225 square feet.
15 square yards = 135 square feet.
15 square yards = 135 square feet.
225 square feet.
15 square feet
22' x 15' = 330 square feet.
15 feet x 3 feet = 45 square feet
225 square feet