Grout Calculator
Calculate how much grout you need for tile installation.
Enter tile size, joint width, and area to get the amount in pounds or kg.
Grout Needed
How Grout Quantity Is Calculated
Grout fills the joints between tiles. The amount needed depends on tile size, joint width, joint depth, and tile thickness.
Grout Volume Formula:
Grout (kg) = [(L + W) / (L × W)] × J × D × A × ρ
Where:
- L = tile length (mm)
- W = tile width (mm)
- J = joint width (mm)
- D = joint depth (mm, usually = tile thickness)
- A = total tiled area (m²)
- ρ = grout density (approx. 1.7 kg/L for sanded, 1.5 for unsanded)
Simplified Practical Formula: Most tile manufacturers provide a coverage rate in kg/m² for their grout. Multiply that by your area and add 10% waste.
Worked Example: 300mm × 300mm tiles, 3mm joints, 10mm thick tiles, covering 15 m²:
- Joint factor = (300 + 300) / (300 × 300) = 600 / 90,000 = 0.00667
- Volume per m² = 0.00667 × 3 × 10 = 0.2 liters/m²
- Total volume = 0.2 × 15 = 3.0 liters
- Weight = 3.0 × 1.7 = 5.1 kg + 10% waste = 5.6 kg
Reference Values:
- Small tiles (100×100mm), 2mm joints: ~0.8 kg/m²
- Medium tiles (300×300mm), 3mm joints: ~0.5 kg/m²
- Large tiles (600×600mm), 5mm joints: ~0.4 kg/m²
- Always add 10–15% for waste, cuts, and uneven surfaces
- Sanded grout: joints wider than 3mm; Unsanded: joints 3mm or narrower