How many 20x20 ceramic tiles do you need for a 15'x20' room?

Answer 1

First we need to calculate the square footage of the room.

15*20 = 300 square feet

Now we need to know how many square feet each tile covers.

20" = 1.667~ square feet

1.6672 = 2.78 square feet.

Now we divide the area of the tiles into the area of the room.

300/2.78 = 108 tiles.

This gives the exact number of tiles you need mathematically. Realistically you need to account for cutting and breaking. It's safe to round that up to 120 tiles.