Quick answer
Divide the area you are tiling by the area of one tile, then add 10 to 15 percent for cuts and breakage. A 48 square foot bathroom floor needs 56 tiles at 12 x 12 inches with 15 percent waste, which is 4 boxes at 15 square feet per box.
How many tiles for common areas
Tile counts by area for three popular sizes, including 15 percent waste.
| Area | Area to buy | 12 x 12 in tiles | 12 x 24 in tiles | 3 x 6 in subway tiles |
|---|---|---|---|---|
| 20 sq ft | 23 sq ft | 23 | 12 | 184 |
| 30 sq ft | 34.5 sq ft | 35 | 18 | 276 |
| 40 sq ft | 46 sq ft | 46 | 23 | 368 |
| 50 sq ft | 57.5 sq ft | 58 | 29 | 460 |
| 60 sq ft | 69 sq ft | 69 | 35 | 552 |
| 80 sq ft | 92 sq ft | 92 | 46 | 736 |
| 100 sq ft | 115 sq ft | 115 | 58 | 920 |
| 150 sq ft | 172.5 sq ft | 173 | 87 | 1,380 |
Counts ignore grout joints. For mosaics sold on sheets, divide the area to buy by the coverage of one sheet instead.
How do you calculate how many tiles you need?
The calculator works out the area in square feet, adds your waste percentage, and then answers two different questions: how many individual tiles that is, and how many full boxes you have to buy.
Tile size is entered in inches and converted to square feet by dividing by 144. Boxes are rounded up because stores do not split them, and leftover tiles from the same lot are useful for later repairs.
The formula
- Area = length x width
- Adjusted area = area x (1 + waste %)
- Tile area = (tile length x tile width in inches) / 144
- Tiles = adjusted area / tile area, rounded up
- Boxes = adjusted area / box coverage, rounded up
Worked example
With the starting values in the calculator (Area length: 8 ft, Area width: 6 ft, Second area length: 0 ft, Second area width: 0 ft, Tile length: 12 in, Tile width: 12 in, Box coverage: 15 sq ft, Waste buffer: 15%, Tile box price: $38), the result is 4 boxes at an estimated $152.
- Area = 8 x 6 = 48 sq ft
- Tile area = (12 x 12) / 144 = 1 sq ft
- Tile count = 55.2 / 1, rounded up = 56
What this calculator assumes
- Waste defaults to 15 percent to allow for edge cuts in small rooms.
- Grout joints are ignored, which keeps the tile count slightly on the safe side.
- Box coverage defaults to 15 square feet. Replace it with the number on your box.
- Thinset, grout, trim, and waterproofing are listed as reminders but not sized.
Tips for a more accurate estimate
- Use 10 percent waste for a simple grid in a square room and 15 to 20 percent for diagonal or herringbone layouts.
- Small rooms waste more tile than large ones because a bigger share of tiles get cut at the edges.
- Buy every box at once and check that the lot or shade numbers match.
- Showers and other wet areas need a waterproofing system behind the tile, not just more grout.
Tile Calculator FAQ
How many 12 x 12 tiles do I need for 100 square feet?
Each 12 x 12 inch tile covers 1 square foot, so 100 square feet needs 100 tiles before waste, 110 tiles with 10 percent waste, or 115 tiles with 15 percent waste.
How do I calculate tile for a backsplash?
Measure the length and height of each wall section in feet, multiply to get square feet, and subtract large openings such as windows. Enter the total as the area, then add at least 10 percent waste.
How many tiles come in a box?
It depends on the tile. Divide the square feet printed on the box by the area of one tile. A 15 square foot box of 12 x 24 inch tile holds about 7 or 8 pieces.
How do I calculate square feet for tile?
Measure the length and width in feet and multiply them. For measurements in inches, multiply and divide by 144. Split L-shaped floors into two rectangles and enter the second one as the second area.
How do I calculate tile for shower walls?
Enter the back wall as the first area, for example 5 ft wide by 8 ft tall. Add the two side walls together as the second area, for example 3 + 3 = 6 ft wide by 8 ft tall. Subtract any niche or window, and use 15 percent waste or more for wall tile.
How much tile waste should I add?
Ten percent works for simple layouts. Use 15 to 20 percent for diagonals, patterns, niches, or rooms with many cuts.
Does this include thinset and grout?
The shopping list reminds you to buy thinset, grout, spacers, and trim, but it does not size them. Coverage depends on trowel notch, tile size, and joint width, so use the chart on the bag.
Is tile a good first DIY project?
Small dry floors are more beginner-friendly than showers. Waterproofing mistakes can become expensive.
Use this estimate as a planning starting point. Product coverage, waste, local prices, code rules, and site conditions can change the final amount.