Joint volume, grout mass, and package rounding
Geometry mode calculates joint volume and product mass from entered yield. Coverage mode uses the manufacturer’s coverage per package and does not report joint volume. Both apply your allowance before rounding to whole packages; purchased mass and material cost use those packages.
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. In manufacturer-coverage mode, base packages = tiled area ÷ coverage per package. Apply the allowance, then round once to whole packages; estimated product mass equals unrounded packages × package weight. Joint volume is unavailable in that mode.
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
- Choose metric or square-foot/inch entry and geometry or manufacturer package coverage.
- For geometry, enter actual tile and joint dimensions plus product mass per filled litre. For coverage, enter the coverage stated for your tile/joint combination.
- Choose kilograms or pounds, enter package weight, allowance and package price.
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.
Using coverage per package
Use a coverage figure for the exact tile size, joint width and fill depth in the manufacturer table. Its package size must match your entered package weight. Coverage mode rounds to whole packages and does not infer joint volume or a product yield from its brand name.
Assumptions & limitations
What this calculation assumes
- Geometry mode uses a uniform rectangular grid; coverage mode uses supplied package coverage for the matching tile and joint dimensions.
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.
Which estimate should I use with a product coverage table?
Use coverage per package for the actual tile size and joint width/depth listed by the manufacturer. The package must match the weight you enter. Avoid applying an extra allowance twice when the published coverage already includes it.
Sources & further reading
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