NumberTally Tile Calculator
Tiling a floor? Enter the room size and your tile size to get the floor area, exactly how many tiles to buy (with a waste allowance for cuts and breakage), and how many boxes that means — so you never run short mid-project.
How much extra tile should you buy?
The standard waste allowance is 10% for a straightforward rectangular room. Bump it to 15–20% if the room has lots of corners, angles, or doorways (every cut wastes part of a tile), or if you’re laying tile diagonally — diagonal layouts can waste 15% on their own. Always keep a few spare tiles after the job: dye lots change, and a matching tile in five years is worth more than the few dollars it costs today.
Tips for estimating tile
Measure the room at its widest points — alcoves and jogs count. Subtract only large permanent fixtures (a kitchen island, for example); it’s not worth subtracting a toilet footprint. Grout lines don’t change the tile count enough to matter at this scale. If you’re mixing tile sizes or laying a border pattern, estimate each area separately and add them up.
Frequently Asked Questions
How do you calculate how many tiles you need?
Divide the floor area (in square feet) by the area of one tile (also in square feet), then round up and add 10% for waste. A 12 × 12 in tile covers exactly 1 sq ft, so a 120 sq ft room needs 120 tiles plus 12 extra = 132.
How many 12 × 12 tiles are in a box?
It varies by manufacturer — common counts are 8, 10, or 12 tiles per box (8–12 sq ft of coverage). Check the box label for the coverage in square feet and divide your total by that number, rounding up.
Do you include waste for tile cuts?
Yes — always. 10% is the baseline for simple rooms; use 15–20% for diagonal layouts, rooms with many corners, or inexperienced installers. This calculator applies your chosen percentage automatically.
Should I subtract doorways and closets?
Only subtract large areas you truly won’t tile (a big pantry or island). Small closets and thresholds are usually tiled anyway, and the waste allowance already covers minor overage.
How many tiles cover 100 square feet?
With 12 × 12 in tiles: 100 tiles plus 10% waste = 110. With 24 × 24 in tiles (4 sq ft each): 25 tiles plus waste = 28. Bigger tiles mean fewer pieces but more waste per cut.