The joint-volume approximation uses tile dimensions, joint width, filled depth and a product density factor. Dimensions are converted to millimetres inside the formula. Density is not interchangeable between grout products. Check the specific technical sheet, application conditions and packaging before buying; the calculated mass remains an estimate.
Worked reference example
Illustrative inputs in metres and SI units; the price is an example entered by the user, not a market quotation. Numeric reference verified by the automated test suite.
- Length
- 4
- Width
- 3
- Area deductions (trim tool: length)
- 0
- Tile / paver length
- 0.3
- Tile / paver width
- 0.3
- Joint / board gap
- 0.003
- Depth
- 0.008
- Product density factor (kg/L)
- 1.6
- Allowance
- 10
- Price per purchase unit
- 2
- Result
- 3.3792
- Cost (example currency units)
- 6.7584
Calculation method
m ≈ A × (a + b)/(a × b) × d × j × ρ × (1 + r / 100); a,b,d,j: mmMeasure. Calculate. Build.
- Use actual dimensions and split complex rooms into rectangles.
- Allow for cuts, joints and package sizes. Compare stock formats.
- Combine your results in a shopping list you can save and print.
Sources & limits
Planning estimates; verify measurements and product data before purchasing.
Mapei — Use your grout manufacturer’s density factor and verify actual coverage.
Prices are supplied by you. Area estimates do not establish a feasible cutting arrangement. These tools do not assess structural loads or issue construction approvals.