How to Use the Tile Calculator
What This Calculator Does
The Tile Calculator estimates how many tiles, boxes, pounds of grout, and bags of thin-set adhesive you need for a tiling project. You enter your room dimensions, tile size, waste percentage, and tiles per box — the calculator does the rest instantly, in your browser, with no data sent to a server.
Understanding Each Input
- Room Length & Width — The dimensions of the area to be tiled. For an L-shaped room, split it into two rectangles, run the calculator twice, and add the results.
- Measurement Unit — Choose feet (default, US standard) or metres (metric). The calculator converts metres to feet internally before computing area.
- Waste Factor — Extra tiles purchased to account for cuts, breakage, and pattern offsets. 10% is standard for simple grid layouts; 15–20% for diagonal or herringbone patterns. Keep leftover tiles for future repairs.
- Tile Length & Width — Enter the actual face dimensions in inches. For a nominal 12×12 in tile the actual face may be 11-7/8 in (0.125 in less) due to grout spacing — use the nominal dimension for planning purposes; the difference is negligible at typical room scales.
- Tiles per Box — Printed on the box label, typically alongside total square footage. Common values: 10–20 for 12×12 in, 4–6 for 24×24 in, 50–100+ for small mosaics.
- Grout Joint Width — The gap between tiles. Rectified tiles often use 1/16 in (0.0625 in); standard floor tile typically uses 1/8 in (0.125 in); rustic or handmade tile may use 3/8 in or wider.
Reading the Results
The four summary boxes show room area (sq ft), total tiles needed (including waste), boxes to buy (rounded up), and an estimated grout weight in pounds. The shopping list below breaks these out into a printable checklist with adhesive bags and spacers.
Waste Factor Guidelines
- 5% — Backsplash or accent band; minimal cuts, expert installer.
- 10% — Standard rectangular room, grid layout (most common choice).
- 15% — Rooms with obstacles (toilets, vanities, fireplaces).
- 20% — Diagonal (45°) or herringbone pattern; complex room shape.
Grout and Adhesive Notes
Grout quantity is estimated using the standard industry formula based on tile dimensions, joint width, and assumed tile depth of 3/8 in. This is a planning estimate — always read the coverage chart on the specific grout bag you purchase because coverage varies by brand, application method, and whether the grout is sanded or unsanded.
Thin-set adhesive coverage is estimated at approximately 45 sq ft per 50 lb bag using a 3/16 in notched trowel (floor standard). Wall tile applied with a smaller V-notch trowel will cover more area per bag. Consult the product's technical data sheet for exact coverage.
Limitations
This calculator assumes a rectangular (or square) tiled area. It does not account for:
- Non-rectangular rooms (use two rectangles for L-shapes)
- Curved walls or radius layouts
- Trim tiles, bullnose, or border tiles (add these separately)
- Levelling compound or waterproofing membrane requirements
- Tile price or labour cost — results are material quantities only