How to use
Enter the floor or wall area, the tile size and thickness, the grout joint width and the waste allowance. Add how many tiles come in a box and the thinset usage. You’ll see how many tiles and boxes to buy, plus estimates for grout and thinset.
Don’t know the area? In “What to tile” choose the floor or the walls and enter the room size: for walls the calculator takes the perimeter × tiling height and subtracts doors and windows. Waste depends on the pattern — about 10% for straight, 15% for diagonal and 20% for herringbone — and is filled in when you pick one.
How it’s calculated
- Each tile plus its joint takes up (length + joint) × (width + joint). Tiles = area ÷ that × (1 + waste), rounded up.
- Boxes = tiles ÷ tiles per box, rounded up.
- Grout, using the formula grout manufacturers publish: usage per area = (A + B) ÷ (A × B) × tile thickness × joint width × 1.6, with A and B the tile length and width in millimeters.
- Thinset = area × thinset usage.
How much waste to allow
- 5–10% for a straight lay with plain tile.
- 10–15% for diagonal or herringbone patterns, large-format tile and rooms with lots of cuts.
- Keep a few spare tiles for future repairs — the same dye lot is hard to find years later.
Thinset usage
It depends on the trowel notch and is printed on the bag. As a rough guide, a 50-lb bag covers about 90–100 sq ft with a 1/4 × 1/4 in square-notch trowel (about 0.5 lb/sq ft) and about 40–50 sq ft with a 1/4 × 3/8 in or 1/2 in notch for large tile (about 1–1.25 lb/sq ft). The default is 1 lb/sq ft.
Examples
- 100 sq ft of floor, 24 × 12 in tile, 3/8 in thick, 1/8 in joints, 10% waste: 55 tiles, 7 boxes of 8, about 4.9 lb of grout and 100 lb of thinset (two 50-lb bags).
- 60 sq ft of 12 × 12 in tile, 5/16 in thick, 1/8 in joints, 10% waste, 10 per box: 65 tiles, 7 boxes, about 3.3 lb of grout.
FAQ
The box already lists square feet — why count tiles? To double-check: at 16 sq ft per box and 55 tiles needed, it’s still 7 boxes.
Why so little grout? Narrow joints with large tile really don’t need much. Buy the smallest bag that covers it, with a bit to spare.
For laminate or vinyl plank, use the flooring calculator.