How we calculate: tiling
Every formula and default figure our tiling calculators use. Each figure can be changed in its calculator to match your product. See how we calculate for the method behind all of them.
Tile adhesive calculator
Open the tile adhesive calculator
- Adhesive (kg) = area (m²) × coverage for your trowel notch (kg/m², from the bag) × bed factor × (1 + waste)
- Bags = kg ÷ bag size, rounded up
- Primer (L) = area ÷ primer coverage (m²/L, from the bottle)
Coverage depends on the product and the notch: the bag or the maker's chart is the figure to use.
Large-format tiles usually need back-buttering as well as a notched bed; follow the adhesive maker's guidance.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Coverage from the bag for your notch | Enter from the bag, pack or tin | Typical value Not yet checked against the source | From your product Depends on the product and trowel notch; read the bag or maker's chart. |
| Bed factor: Standard notched bed | Enter from the bag, pack or tin | Our assumption Not yet checked against the source | Our choice: change it to suit your job Researcher to source from adhesive makers (Mapei, BAL, Ardex). |
| Bed factor: Solid bed | 1 × | Our assumption Not yet checked against the source | Our choice: change it to suit your job brief v2 TA1 (solid-bed factor 1.0). Researcher to confirm against adhesive makers' charts. |
| Bed factor: Back-buttered | Enter from the bag, pack or tin | Our assumption Not yet checked against the source | Our choice: change it to suit your job Researcher to source from adhesive makers (Mapei, BAL, Ardex). |
| Waste allowance | 10 % | Our assumption Not yet checked against the source | Our choice: change it to suit your job brief v2 TA1 (10%). |
| Bag size | Enter from the bag, pack or tin | Common UK size Not yet checked against the source | From your product Enter from the bag. |
| Primer coverage | Enter from the bag, pack or tin | Typical value Not yet checked against the source | From your product From the primer bottle. |
| Tile side above which the maker says to back-butter | To be confirmed from the source | Regulation or HSE figure Adhesive maker's guidance on large-format tiles (back-buttering) Not yet checked against the source | Source to be added by the Researcher brief v2 T1. Researcher to source the tile size above which makers say to back-butter. |
| Table | Clause | Nations | Status |
|---|---|---|---|
| Tile adhesive coverage by trowel notch | Adhesive makers' coverage charts (e.g. Mapei, BAL, Ardex): product-specific | UK-wide | 0/4 values entered Not yet checked against the source |
Tile calculator
- Tiles = area × (1 + waste) ÷ ((tile length + joint) × (tile width + joint)), rounded up
- Boxes = tiles ÷ tiles per box, rounded up
Tile adhesive and grout have their own calculators: the right amount depends on the product, the trowel notch and the joint, so they need their own inputs.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Waste allowance: Straight | 10 % | Our assumption Not yet checked against the source | Our choice: change it to suit your job Cuts and breakages, straight lay. |
| Waste allowance: Diagonal or herringbone | 15 % | Our assumption Not yet checked against the source | Our choice: change it to suit your job More cuts on diagonal and herringbone. |
| Tiles per box | Enter from the bag, pack or tin | Common UK size Not yet checked against the source | From your product Enter from the box. |
Grout calculator
- Joint volume (L) = area (m²) × (tile length + tile width) ÷ (tile length × tile width) × joint width × joint depth × 1000, with sizes in metres
- Grout (kg) = joint volume (L) × density (kg/L, from the bag) × (1 + waste)
- Bags = kg ÷ bag size, rounded up; sealer (L) = area ÷ sealer coverage
Grout density varies by product (cement grout, epoxy, ready-mixed), so take it from the bag or the maker's calculator.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Grout density | Enter from the bag, pack or tin | Typical value Not yet checked against the source | From your product Depends on the product; read the bag or maker's chart. |
| Waste allowance | 10 % | Our assumption Not yet checked against the source | Our choice: change it to suit your job Cuts and breakages, straight lay. |
| Bag or tub size | Enter from the bag, pack or tin | Common UK size Not yet checked against the source | From your product Enter from the bag. |
| Grout sealer coverage | Enter from the bag, pack or tin | Typical value Not yet checked against the source | From your product From the sealer bottle. |