Tile Calculator
A free tile calculator. Enter your room dimensions and tile size, and get the exact number of tiles, the boxes to buy with waste included, and an optional cost estimate.
This free tile calculator turns your room measurements into an order list: enter the room length and width in feet, pick your tile size, and get the tiles needed, boxes to buy with a standard 10 percent waste allowance, and an optional cost estimate.
Your tile estimate
Estimates only. Boxes and coverage vary by product, so confirm tiles per box and actual tile size on the label. This is general information, not professional advice. See Terms of Use.
How much extra tile to order
The industry standard is 10 percent extra for a straight lay, where tiles sit in a simple grid with straight grout lines. That buffer covers cuts at the room edges, a few broken or chipped tiles, and spares in case one cracks years from now when the original dye lot is gone. Enter your room above and the calculator applies it automatically.
For a diagonal lay, plan on 15 percent. Setting tiles at 45 degrees means nearly every tile along the walls gets cut twice, and those triangular cutoffs rarely fit anywhere else. Herringbone and chevron patterns waste at least as much, and many installers plan 20 percent for those layouts because almost every perimeter tile is a custom cut.
Rooms with obstacles deserve a generous margin rather than a tight one. Every doorway, toilet flange, floor vent, and inside corner turns whole tiles into partial ones, and L-shaped rooms and hallways waste more than a clean rectangle. Measure the true floor area, subtract nothing, and round up.
Finally, buy it all in one purchase. Tile from different production runs can vary slightly in shade, and a dye lot mismatch shows under daylight even when tiles look identical in the box. Your waste allowance doubles as a repair stock for the life of the floor, so store the leftovers flat in a dry place with the box label attached.
Tile calculator questions
How many tiles do I need for a 12x12 room?
A 12 by 12 foot room is 144 square feet. With standard 12x12 inch tiles, each covering 1 square foot, you need 144 tiles before waste. Adding the standard 10 percent straight-lay allowance brings that to 159 tiles, or 16 boxes of 10.
What is the 10 percent rule for tile?
The 10 percent rule says to order 10 percent more tile than the room area requires for a straight grid layout. The extra covers cuts along walls, chipped or broken tiles, and spares for future repairs. Diagonal layouts use a 15 percent allowance because angled cuts waste more material.
How many boxes of tile do I need?
Divide the total tiles you need, including waste, by the tiles per box, then round up to the next whole box. Box counts vary, commonly 5 to 12 tiles per box, so check the label and enter the count above.
How do you calculate tile for a diagonal layout?
Calculate the room area in square feet, divide by the coverage of one tile, then add 15 percent instead of 10 percent. Tiles set at 45 degrees get cut on both edges along every wall, and those triangular cutoffs rarely fit anywhere else, so waste runs higher.
Should I buy extra tile for future repairs?
Yes. Keep the leftovers from your 10 percent allowance. Tile from a different production run can vary slightly in shade, so matching a cracked tile years later is difficult. Store the spares flat in a dry place with the box label so you know the exact product.