Understanding your result
Joint volume comes from the tile-and-joint geometry. Product mass uses your yield-density input and allowance. Package rounding is separate, so the purchased mass can be higher than the application estimate.
For the tiles themselves, the Tile Calculator estimates tile and box quantities with a separate waste allowance.
The formula
The repeating cell includes one tile and its share of the surrounding joints. Subtracting the tile-area fraction avoids double-counting joint intersections. One square metre filled to one millimetre depth is one litre. Multiply by product mass per filled litre and the allowance.
Worked example
Ten square metres of 300 mm square tiles with 3 mm joints filled 8 mm deep contain about 1.576 L of joint space. At 1.6 kg per filled litre and 10% allowance, the estimate is 2.774 kg, requiring two 2.5 kg packages.
How to use this calculator
- Enter the installed tiled area including its joints.
- Measure tile size and the joint width and actual fill depth.
- Use manufacturer yield data, choose an application allowance, and enter package weight.
Density must match packaged yield
For a powder product, use the dry product mass needed to create one litre of filled joint, as derived from the manufacturer’s yield information. Loose powder density or mixed wet density may not describe that relationship. A product-specific coverage table is preferable when available; this geometric estimator cannot infer yield from a brand name.
Grid geometry and real consumption
The model treats the surface as repeating rectangular tiles with uniform full-depth joints. Perimeter details, irregular tile shapes, rounded edges, and gaps below the tile are not individually modeled. Rough surfaces and cleanup can consume additional material. Keep those effects in a deliberate allowance rather than changing tile dimensions to force a desired result.
Assumptions & limitations
What this calculation assumes
- Uniform rectangular grid with equal joint widths and depths.
What to keep in mind
- Not for sealant movement joints, mosaics with irregular gaps, or adhesive quantities.
Common questions
Is grout depth always tile thickness?
No. Use the depth actually available for grout after adhesive and joint preparation, following the product instructions.
Why might a manufacturer calculator differ?
Its product-specific yield, application allowance, and geometry assumptions may differ. Prefer the manufacturer’s coverage guidance for the exact product.