Tiles are counted by how many fit in the area once you allow for the grout line, then rounded up to whole boxes.
Tile calculator
Enter the area, the tile size and the grout joint.
Enter your numbers to see the result.
How it works
Each tile plus its grout joint covers (length + joint) x (width + joint). Divide the area by that and add extra for cuts and breakage. Divide by tiles per box and round up.
How much extra?
Straight layouts in square rooms cut the fewest tiles. Diagonal, herringbone and large-format tiles waste more, and so do rooms with lots of corners. Keep a few spare tiles after the job: matching a discontinued tile years later is hard.
Buy from one lot
Tile color can vary between production runs. Check that every box has the same lot number.
Frequently asked questions
How many 12 x 24 tiles for 100 sq ft?
Each covers about 2 sq ft, so about 50 tiles, plus extra for cuts.
How many tiles in a box?
It is printed on the box, usually with the square feet the box covers.
Should grout lines be counted?
Yes. They add a little coverage per tile, which matters on big floors.