How many tiles do I need?
Measure the floor or wall, and read the tile size and how many tiles come in a box on the box or product page. Each tile takes up its own size plus one grout joint, so wider joints mean slightly fewer tiles.
Some tiles get cut at the edges and some break, and a few spares make repairs easy later. MSI and Daltile both recommend buying about 10% more tile than the area needs, which is where the calculator starts.
Source MSI · How much wall tile do I need? (extra for cuts, patterns and diagonals) ↗Daltile · Tile FAQs, "What is Attic Stock?" ↗
How to calculate tiles
Here it is with your numbers:
- Multiply the length by the width: 12 × 10 = 120 sq ft.
- Add a 1/8 in joint to the tile's length and width, and multiply: (12 + 0.125) × (12 + 0.125) = 147.0156 sq in.
- Change it to square feet (144 sq in make 1 sq ft): 147.0156 ÷ 144 = 1.0209 sq ft.
- Divide the area by the space one tile takes: 120 ÷ 1.0209 = 117.5385 tiles.
- Add 10% for waste: 117.5385 × 1.1 = 129.2924 tiles.
- Round up to whole tiles: 130.
- Divide by the tiles in a box: 130 ÷ 10 = 13 boxes.
It means buying 13 boxes of 10: 130 tiles for 120 sq ft.
Tile comes in whole boxes, so always round up. Daltile suggests storing the spare tiles: a later batch can differ slightly in shade, so spares from the same lot match best.
Source Common Core State Standards · Grade 3, area of rectangles (3.MD.C.7) ↗
How much extra tile to buy
| Layout | Extra |
|---|---|
| Straight layout, kept as spares (MSI, Daltile) | 10% |
| Wall tile with a fancy shape or pattern (MSI) | 15% |
| Diagonal layout (MSI) | 20% more |
MSI's diagonal figure comes on top of the usual 10 – 15%.
Grout joint sizes
There is no set standard for joint width, the Tile Council of North America says. Its rule of thumb: a joint at least twice the difference between the largest and smallest tiles in the box looks even. Under 1/8 in takes unsanded grout, and 1/8 in or more sanded grout.
Source Tile Council of North America · FAQ: grout joint size and sanded or unsanded grout ↗
Tiles for 100 square feet
Tiles to buy for 100 sq ft, with 10% extra for waste.
| Tile | No joint | 1/8 in joints |
|---|---|---|
| 3 × 6 in | 880 | 828 |
| 4 × 4 in | 990 | 931 |
| 6 × 6 in | 440 | 423 |
| 6 × 24 in | 110 | 108 |
| 12 × 12 in | 110 | 108 |
| 12 × 24 in | 55 | 55 |
| 18 × 18 in | 49 | 49 |
| 24 × 24 in | 28 | 28 |
FAQs
How many tiles do I need?
Divide the area by the space one tile takes with its grout joint, then add extra for cuts and spares. A 12 × 10 ft floor in 12 × 12 in tiles with 1/8 in joints takes 117.54 tiles; with MSI's 10% extra that's 130 tiles, or 13 boxes of 10.
Source MSI · How much wall tile do I need? (extra for cuts, patterns and diagonals) ↗
How do you calculate square feet for tile?
Measure the length and width in feet and multiply them: 12 × 10 ft is 120 sq ft. Change inches to feet first by dividing by 12, and split an L-shaped room into rectangles and add them.
Source Common Core State Standards · Grade 3, area of rectangles (3.MD.C.7) ↗
How do you grout tile?
Start by picking the joint and the grout to match it. The Tile Council of North America says joints narrower than 1/8 in take unsanded grout, and 1/8 in or wider take sanded grout; joints over 3/8 in usually need a more heavily sanded grout. Keep grout off the tile's beveled edge.
Source Tile Council of North America · FAQ: grout joint size and sanded or unsanded grout ↗
How do you create patterns with floor tiles?
Diagonal and patterned layouts need more cut tiles, so buy more. MSI recommends 15% extra for wall tile with a fancy shape or pattern, and for a diagonal layout 20% more on top of the usual 10 – 15%.
Source MSI · How much wall tile do I need? (extra for cuts, patterns and diagonals) ↗
Sources
- MSI: How much wall tile do I need? (extra for cuts, patterns and diagonals)
- Daltile: Tile FAQs, "What is Attic Stock?"
- Tile Council of North America: FAQ: grout joint size and sanded or unsanded grout
- Common Core State Standards: Grade 3, area of rectangles (3.MD.C.7)