Tile calculator
Enter the area, the tile size and your grout joint. The joint width matters more than you’d think with small tiles.
Tiles needed
44 tiles
- Boxes
- 5 boxes
- Area
- 40 sq ft
How it works
Each tile effectively covers its own size plus one grout joint in each direction. The calculator divides the area (in square inches) by that footprint, adds your waste allowance, and rounds up.
Example
With area length 8 ft, area width 5 ft, tile width 12 in, tile length 12 in, grout joint 0.125 in, waste 10%, tiles per box 10, the answer is 44 tiles.
Tips before you buy
- Use 10% waste for a straight grid and 15% or more for diagonal layouts, large-format tile or rooms with lots of cuts.
- Keep a few spare tiles after the job. Matching a discontinued tile later is often impossible.
- Lay out a dry row before setting tile so you don’t end up with a thin sliver at one wall.
Common questions
How many 12×12 tiles do I need for 100 square feet?
About 98 tiles before waste with a 1/8 inch joint, or 108 with 10% extra.
How much extra tile should I buy?
10% for a simple floor. 15–20% for diagonal patterns, herringbone or large tiles that break more often.
Does grout joint size change how many tiles I need?
Slightly. Wider joints mean fewer tiles, and the effect is bigger with small tiles like mosaics.