Tile Calculator
Tile is sold by the piece or the box, but your floor is square feet. Enter the room and your tile size — the calculator converts and adds waste for cuts.
Tile Calculator
About this tile calculator
Tile math has one trap: tiles are sold by the piece, floors are measured in square feet, and cuts turn perfect rectangles into scrap. This calculator bridges all three — floor area, tile size, and a waste allowance that covers edge cuts, broken tiles, and the occasional learning experience.
The waste percentage is the judgment call. A straight grid lay in a square room wastes about 10%. Diagonal patterns, L-shaped rooms, and floors full of doorways push it to 15% or more, because every angled cut sacrifices most of a tile. Large-format tiles (24×24) break more often during cutting, so be generous.
Buy all boxes from the same dye lot — the lot code is printed on the box. Tile color shifts slightly between production runs, and two lots on one floor can show a visible tone change. Keep a few spare tiles after the job; manufacturers discontinue lines constantly.
How to use
- Measure the floor length and width in feet. For L-shaped rooms, split into rectangles and run each separately, then add.
- Select your tile size and a waste allowance (15% for diagonal layouts).
- Press Calculate, then divide the tile count by the box's tiles-per-box for boxes to buy.
- Buy everything from one dye lot and keep spares.
Good to know
- Rectangular tiles (e.g. 12×24) are supported — enter tile length and width. Mosaics and complex patterns still need manual layout planning.
- Grout, thinset, backer board, and underlayment are separate materials — budget them from the same square footage.
- Does not account for pattern matching or centering layouts, which can add waste.
Frequently asked questions
How many tiles do I need for 100 square feet?
With 12×12 in tiles and 10% waste: 100 sq ft ÷ 1 sq ft per tile = 100 tiles × 1.10 = 110 tiles. With 24×24 tiles (4 sq ft each): 28 tiles with waste.
How much extra tile should I buy for waste?
10% for straight layouts in simple rooms, 15% for diagonal patterns or rooms with many cuts. First-time tilers should lean to 15%.
What is a dye lot and why does it matter?
The production batch printed on the tile box. Color varies slightly between batches, so mixing lots can leave a visible tone shift across your floor.
How do you calculate floor tiles?
Floor area in sq ft ÷ area of one tile in sq ft, plus 10–15% waste, rounded up to whole tiles.
Should I include grout lines in tile calculations?
No — grout lines are small enough that the waste allowance absorbs them. Spacers of 1/8 to 1/4 inch don't change the tile count.