Tile Grout Calculator
Calculate grout bags needed from tile size, total area, and joint width.
Returns pounds of sanded or unsanded grout for floors, walls, and backsplashes.
Tile grout quantity depends on the tile size, grout joint width, tile thickness, and grout coverage rate. Under-ordering means a mid-job color mismatch if the dye lot differs — always order a little extra.
Grout Coverage Formula:
Pounds Needed = (Tile Length + Tile Width) / (Tile Length × Tile Width) × Joint Width × Tile Thickness × Coverage Factor × Area
In simplified form using a pre-calculated coverage table, the formula reduces to:
Pounds per 100 sq ft = Area Factor × Joint Width (inches) × Tile Depth (inches)
A practical shortcut used by installers:
Lbs per sq ft = (A + B) / (A × B) × Joint × Depth × 0.1875
Where A and B are tile dimensions in inches.
Worked example: Tile: 12 × 12 inches Grout joint: 1/8 inch (0.125 in) Tile thickness: 3/8 inch (0.375 in) Area: 120 sq ft
Lbs/sq ft = (12 + 12) / (12 × 12) × 0.125 × 0.375 × 0.1875 = (24 / 144) × 0.125 × 0.375 × 0.1875 = 0.1667 × 0.0088 = 0.00147 lbs/sq ft → too small alone…
Practical coverage (pre-mixed grout bags, from manufacturer data):
| Tile Size | Joint | Bags per 100 sq ft |
|---|---|---|
| 2×2 | 1/8" | 4–5 bags |
| 4×4 | 1/8" | 2–3 bags |
| 6×6 | 3/16" | 2 bags |
| 12×12 | 3/16" | 1–1.5 bags |
| 18×18 | 1/4" | 1–1.5 bags |
Grout types: Sanded grout for joints wider than 1/8 inch; unsanded for 1/16–1/8 inch. Using sanded grout in narrow joints scratches polished tile.
Always add 10–15% for waste, cuts, and coverage variability. Store leftover grout sealed in a cool, dry place for future repairs — color matching later is nearly impossible.