Grout fills the joints, so what matters is how much joint there is per square foot: small tiles and wide joints use a lot, large tiles with narrow joints use very little.
The calculator uses the formula published by Mapei: (A + B) ÷ (A × B) × joint width × tile thickness × density, with sizes in millimeters.
How to use
- Enter the area to grout.
- Pick the tile size and type the grout joint width.
- Type the tile thickness (the joint is filled to the full depth of the tile).
- Choose the package size to see how many bags or boxes to buy.
Grout per area (lb/100 sq ft)
| Tile (thickness) | Joint 1/16 in | Joint 1/8 in | Joint 3/16 in |
|---|---|---|---|
| 12×12 in (5/16 in) | 2.73 | 5.46 | 8.19 |
| 12×24 in (5/16 in) | 2.05 | 4.1 | 6.14 |
| 18×18 in (5/16 in) | 1.82 | 3.64 | 5.46 |
| 24×24 in (3/8 in) | 1.71 | 3.41 | 5.12 |
| 6×24 in (5/16 in) | 3.41 | 6.83 | 10.24 |
| 24×48 in (3/8 in) | 1.28 | 2.56 | 3.84 |
Density 1.6 (cement grout), without waste.
The grout formula
kg per m² = (A + B) ÷ (A × B) × C × D × 1.6, where A and B are the tile length and width, C the tile thickness and D the joint width, all in millimeters. For a 75 × 150 mm wall tile 6 mm thick with a 3 mm joint: 225 ÷ 11,250 × 3 × 6 × 1.6 = 0.58 kg/m², which is the figure in Mapei's own table. In US units, 1 kg/m² is about 20.5 lb per 100 sq ft.
Sanded or unsanded
Unsanded grout is for joints up to 1/8 in; sanded grout for wider joints. Epoxy grout has a different density, so check the coverage table on its package.
Where the numbers come from
Coverage and consumption figures come from manufacturer data sheets and published standards: