Tile grout Calculator: measuring notes and method
Use actual joint width and fill depth
Measure the tile face and use the width and depth of the filled joint. A joint partially occupied by adhesive may not use the full tile thickness as grout depth.
Compare with the chosen grout guide
Irregular mosaics, textured edges and tooling losses can differ from the regular-grid model. Keep movement joints separate from the grouted-joint quantity.
Formula
Joint fraction = 1 − tile face area ÷ [(tile length + joint) × (tile width + joint)]. Mass = area × joint fraction × depth × density, with waste.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total surface area
- 24 m²
- Tile length
- 300 mm
- Tile width
- 300 mm
- Joint width
- 3 mm
- Filled joint depth
- 8 mm
- Grout density
- 1,700 kg/m³
- Bag size
- 5 kg
- Waste allowance
- 10 %
Grout required: 7.0745 kg
Imperial worked example
- Total surface area
- 258.3339 ft²
- Tile length
- 11.811 in
- Tile width
- 11.811 in
- Joint width
- 0.1181 in
- Filled joint depth
- 0.315 in
- Grout density
- 106.1275 lb/ft³
- Bag size
- 11.0231 lb
- Waste allowance
- 10 %
Grout required: 15.5966 lb
Follow the calculation
Lengths in this working are in metres.
- Joint area fraction = 1 − (0.3 × 0.3) ÷ [(0.3 + 0.003) × (0.3 + 0.003)] = 0.019704.
- Mass = 24 × joint fraction × 0.008 × 1,700 × 1.1 kg. Divide by 5 kg for bags and round up.
Reviewed 19 October 2026. How calculations are checked · Report a correction