How many tiles you'll need for a room, based on room size, tile size and a waste allowance.
Rooms are usually measured in feet while tiles are sold by inch dimensions (e.g. 12×12 in). The calculator converts tile length and width to feet before dividing room area by tile area, so you don't have to convert units yourself.
"Tiles (exact)" is the raw room-area-divided-by-tile-area figure with no rounding. "Tiles to Buy" adds your waste allowance percentage and rounds up to a whole tile, since you can't purchase a fraction of a tile and cuts always leave offcuts.
10% is a common default for simple layouts. Diagonal layouts, intricate patterns, or rooms with lots of cuts around fixtures typically need a higher allowance — adjust the waste field to match your layout's complexity.