Tile Calculator
Estimate how many tiles and boxes you need for a floor, backsplash or shower – plus thinset, grout and total tile cost.
Formulas shown on this page · Last reviewed October 2026
How the tile calculator works
Enter the length and width of the area, the tile size and the grout joint. The calculator adds your waste percentage, then divides by the area one tile covers including half a joint on each side.
tiles = area (sq ft) × (1 + waste) ÷ [(tile W + joint) × (tile H + joint) ÷ 144]
boxes = area × (1 + waste) ÷ sq ft per box, rounded up
thinset bags = area ÷ 95 (50 lb bag, 1/4 in notch)
Tiles per 100 square feet (no waste)
| Tile size | Tiles per sq ft | Tiles per 100 sq ft |
|---|---|---|
| 4 × 4 in | 9 | 900 |
| 6 × 6 in | 4 | 400 |
| 12 × 12 in | 1 | 100 |
| 12 × 24 in | 0.5 | 50 |
| 24 × 24 in | 0.25 | 25 |
Recommended waste by layout
| Layout | Waste |
|---|---|
| Straight / grid | 10% |
| Diagonal | 15% |
| Herringbone, mosaics, small rooms | 15–20% |
Practical tips
- Measure each room separately and add them up; subtract only large permanent areas such as a tub or kitchen island.
- Keep one or two spare boxes after the job – discontinued tile is nearly impossible to match for repairs.
- Price shown is the tile only. Backer board, underlayment, spacers and sealer are extra.
- The grout figure is an estimate; always check the manufacturer's coverage chart for your tile and joint size.
Frequently asked questions
How many 12×12 tiles do I need for 100 square feet?
Each 12×12 tile covers 1 sq ft, so you need 100 tiles for the floor itself and 110 with the standard 10% waste. With a 1/8 inch grout joint each tile effectively covers 1.02 sq ft, so about 108 tiles are enough. If tiles are sold at 15 sq ft per box, 110 sq ft is 8 boxes.
How much waste should I add for tile?
Add 10% for a straight lay, 15% for diagonal or herringbone patterns and up to 20% for small rooms with many cuts or large-format tile. Buy all boxes at once so the dye lots match.
How much thinset do I need?
A 50 lb bag of thinset covers roughly 95 sq ft with a 1/4 inch square-notch trowel, which suits tiles up to about 12 inches. Larger tiles need a 1/2 inch notch and coverage drops to about 40–50 sq ft per bag. So 100 sq ft of 12×12 tile takes 2 bags.
How much grout do I need for 100 square feet of tile?
For 12×12 tile that is 3/8 inch thick with 1/8 inch joints, about 7–8 lb of grout covers 100 sq ft. Smaller tiles and wider joints need far more: 3×6 subway tile at the same joint width uses roughly three times as much.