Grout Calculator
Calculates precision grout volume using the exact mathematical joint-volume formula: (L + W) / (L × W) × Joint Width × Tile Thickness × Tile Area × Specific Gravity.
Formula
Grout Lbs = ((L + W) ÷ (L × W)) × Joint Width × Thickness × Area × 1.6 × (1 + Waste %)
1. Joint Factor = (Tile Length + Tile Width) ÷ (Tile Length × Tile Width) 2. Theoretical Lbs = Joint Factor × Joint Width × Tile Thickness × Area Sq Ft × 1.6 3. Total Lbs with Waste = Theoretical Lbs × (1 + Waste %) 4. Bags = Ceil(Total Lbs ÷ Bag Weight (typically 10 lb or 25 lb))
Inputs
- Total Tiled Area
- Tile Length (Inches)
- Tile Width (Inches)
- Tile Thickness (Inches)
- Grout Joint Width (Inches)
Worked example
Grouting 120 sq ft of large format porcelain tiles with 1/8" spacers.
Outcome: Joint factor is (12 + 24) ÷ (12 × 24) = 0.125. Theoretical grout needed is 0.125 × 0.125 × 0.375 × 120 × 1.6 = 11.25 lbs. Adding 15% waste equals 12.94 lbs (recommend one 25-lb bag or two 10-lb bags).
When should I use epoxy grout instead of cement grout?
Epoxy grout is 100% waterproof, highly stain-resistant, and never requires sealing. It is ideal for shower floors, kitchen counters, and commercial kitchens, although it sets quickly and requires careful cleanup.