Transparent method
The formula
Worked example
Example inputs
How to interpret the result
A tile order calculated from bare square footage alone runs short almost every time, because cuts around edges, corners and obstacles waste partial tiles that a straight area calculation doesn't account for, and a diagonal layout wastes noticeably more than a straight lay, since more tiles need angled cuts to fit the room's edges.
Before you rely on it
What to check
Match the waste-allowance percentage to the actual layout pattern planned, not a flat default, since diagonal and intricate patterns genuinely need more allowance than a straight lay.
The common error
Where people go wrong with tile flooring calculator
Ordering tile based on raw square footage with no waste allowance, or applying a straight-lay allowance to a diagonal pattern. Either mistake leaves a room short of tile partway through installation.
Sensitivity evidence
How room length (ft) changes the tiles needed
| Room length (ft) | Tiles needed | Room area (sq ft) |
|---|---|---|
| 10 | 111 | 100 |
| 11 | 122 | 110 |
| 12worked example | 132 | 120 |
| 13 | 143 | 130 |
| 14 | 154 | 140 |
Every input, tested
Which input moves the tiles needed most
| Input | Tested from | To | Tiles needed at each end | Swing |
|---|---|---|---|---|
| Room width (ft) | 9 | 11 | 119 to 146 | 27 (20%) |
| Tile length (in) | 11 | 13 | 144 to 122 | 22 (17%) |
| Tile width (in) | 11 | 13 | 144 to 122 | 22 (17%) |
| Room length (ft) | 11 | 13 | 122 to 143 | 21 (16%) |
| Waste allowance | 8.0% | 12.0% | 130 to 135 | 5 (3.8%) |
Two variables at once
Tiles needed by room length (ft) and room width (ft)
| Room length (ft) \ Room width (ft) | 8 | 10 | 12 |
|---|---|---|---|
| 10 | 88 | 111 | 132 |
| 11 | 97 | 122 | 146 |
| 12 | 106 | 132 | 159 |
| 13 | 115 | 143 | 172 |
| 14 | 124 | 154 | 185 |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Room length (ft) | 12 |
| Room width (ft) | 10 |
| Tile length (in) | 12 |
| Tile width (in) | 12 |
| Waste allowance | 10.0% |
| Tiles needed | 132 |
| Room area (sq ft) | 120 |
Where the inputs come from
Enter the room length and width in feet, the tile length and width in inches and the waste allowance as a percent. Measure the actual floor, subtracting fixed cabinets or islands that will not be tiled. Use the size of the tile, not the grout-included pattern size, and choose a waste allowance of 10% for a simple layout and 15% or more for diagonal patterns or rooms with many cuts. Round up to full tiles, and to full boxes.
When the result stops applying
Large-format tiles and patterns such as herringbone increase waste. Uneven walls and floors mean tiles at the edges must be cut and some pieces cannot be reused. The tool ignores grout width, though it matters for exact counts. Tiles are sold by box, so the number of boxes matters more than the tile count.
What to compare it with
Get the area on the square footage and rectangle calculators, plan flooring on the flooring and carpet pages, and estimate mortar or base on the material volume calculator. The paver and wallpaper calculators cover similar surface jobs, and the paint calculator handles walls.
People also ask
Frequently asked questions
How much extra tile should I buy?
About 10% for straight layouts and 15% or more for diagonal or complex patterns, plus a spare box for future repairs.
Does grout width affect the tile count?
Slightly. A wider grout line means fewer tiles per square foot, but the effect is small compared with waste.
Why keep leftover tiles?
Tiles from a different production batch can vary in color, so spares from the original order make repairs match.