300 × 300 mm floor tiles, 20 m²
Input 8 mm thick, 3 mm joints, density 1.6, 5 kg bags, 10% waste.
Result 0.256 kg/m² → 5.63 kg total → 2 bags (12.4 lb).
Tile Grout Calculator
Home & RenovationCalculate grout in kilograms from tile size, joint width, tile thickness and the area you are tiling.
Your inputs
Result
Grout needed
—
kg
- Bags to buy — bags
- Weight in pounds — lb
- Grout per m² — kg/m²
- Tiling area — m²
Change any input and the result updates instantly.
Formula and rules
- Grout per m² = ((tile length + tile width) ÷ (tile length × tile width)) × joint width × tile thickness × density
- Total grout = grout per m² × area × (1 + waste allowance)
- Bags = round up (total grout ÷ bag size)
- All tile dimensions and the joint width must be in millimetres; density in kg/L.
Worked examples
600 × 600 mm porcelain, 40 m²
Input 10 mm thick, 2 mm joints, density 1.6, 5 kg bags, 10% waste.
Result 0.107 kg/m² → 4.69 kg total → 1 bag (10.3 lb).
75 × 300 mm subway tiles, 12 m²
Input 8 mm thick, 3 mm joints, density 1.6, 5 kg bags, 10% waste.
Result 0.640 kg/m² → 8.45 kg total → 2 bags.
FAQ
Why does tile size change grout consumption so much?
Grout fills the joint volume between tiles. Smaller tiles create far more joint length per square metre, so a 75 × 300 mm tile uses several times more grout than a 600 × 600 mm tile with the same joint width.
Should I use the tile thickness or the joint depth?
This calculator uses tile thickness as the joint depth, which is correct for full-bed adhesive. If you leave the joint shallower than the tile, reduce the thickness value accordingly.
How much extra should I buy?
10% covers waste, mixing loss and a little touch-up. Keep one unopened bag from the same batch so future repairs match in colour.
Disclaimer: Results follow the formula shown on this page and are for reference only. Real-world quantities vary with materials, technique and conditions, so allow a margin before ordering.