Grout Volume CalculatorFree online other calculator — instant results, no sign-up
Estimate grout volume from a repeating rectangular tile grid.
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About the Grout Volume Calculator
The Grout Volume Calculator estimates the grout needed to fill joints in a repeating rectangular tile grid. It uses the tiled area, tile dimensions, joint width, and joint depth to calculate the joint volume in litres, counting intersecting joints only once.
- Tiled area (m²)
- The total area covered by the tile grid, including its joints, in square metres; the default is 20 m².
- Tile length (mm)
- The length of each tile, excluding the joint, in millimetres; the default is 300 mm.
- Tile width (mm)
- The width of each tile, excluding the joint, in millimetres; the default is 300 mm.
- Joint width (mm)
- The uniform gap between adjacent tiles in millimetres; the default is 3 mm.
- Joint depth (mm)
- The depth of the joint that will actually be filled with grout, in millimetres; the default is 8 mm.
Formula and method
V = A × d × [1 − (l × w) / ((l + j) × (w + j))]. With the default inputs: V = 20 × 8 × [1 − (300 × 300) / ((300 + 3) × (300 + 3))] = 3.152632 L, rounded to six decimal places.
- VEstimated grout volume in litres.
- ATotal tiled area, including joints, in square metres.
- lTile length in millimetres.
- wTile width in millimetres.
- jJoint width in millimetres.
- dFilled joint depth in millimetres.
Model one repeating cell as a tile plus the joint spacing, giving a cell area of (l + j) × (w + j). Subtract the tile area l × w and divide by the cell area to obtain the fraction of the surface occupied by joints. Multiply that fraction by the total tiled area and filled joint depth. With area in m² and depth in mm, the result is directly in litres because 1 m² × 1 mm = 1 L.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Tiled area20 m²
- Tile length300 mm
- Tile width300 mm
- Joint width3 mm
- Joint depth8 mm
Results
- Result3.152632 L
How to use the Grout Volume Calculator
- 1Enter the total tiled area, including joints, in m²; use 20 for the default example.
- 2Enter the tile length and width in mm; the default example uses 300 mm for both.
- 3Enter the joint width in mm; use 3 for the default example.
- 4Enter the actual grout-filled joint depth in mm; use 8 for the default example.
- 5Read the calculated grout volume: the default inputs give 3.152632 L, before any allowance for waste.
Reading your result
The Result row reports the estimated volume of filled grout joints in litres. For the default inputs, Result = 3.152632 L. This is a geometric volume, not a dry grout weight or a recommended purchase quantity; the displayed decimal places do not imply equivalent accuracy on site.
Limitations
The model assumes identical rectangular tiles in a regular repeating grid, uniform joint width, and constant grout-filled depth. It treats the tiled area as including both tiles and joints and does not explicitly count perimeter joints or cut tiles. It excludes waste, mixing losses, voids beneath tiles, and product-specific shrinkage or yield. Irregular layouts, bevelled tile edges, varying depths, and movement joints filled with sealant can make actual grout use differ. Use positive tile dimensions and nonnegative area, joint width, and joint depth.
Common questions
Does tiled area include the gaps between tiles?+
Yes. Enter the full area covered by the repeating tile-and-joint grid, not just the combined face area of the tiles. The formula calculates the joint fraction of that full area.
Should joint depth equal the tile thickness?+
Only if grout fills the joint through that entire thickness. Enter the actual depth available for grout after accounting for adhesive or other material in the joint.
Are the crossings between grout joints counted twice?+
No. The calculator subtracts the tile face area from each repeating cell, so each joint intersection is included only once.
How do I turn the litre result into bags of grout?+
Use the selected product’s published mixed-grout yield in litres per bag. Add an appropriate waste allowance to the calculated volume, divide by that yield, and round up to whole bags; do not assume that one litre equals one kilogram of dry grout.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.