Grout calculator: how much grout you need
The calculator needs JavaScript. The worked example, formula and figures below show exactly how it works, so you can do the sum yourself. A guide, not advice. Check your supplier's or maker's figures before ordering.
Short answer
Worked example
| You enter | Value |
|---|---|
| Area tiled | rectangle 4 m × 2.5 m |
| Tile length | 300 mm |
| Tile width | 300 mm |
| Joint width | 3 mm |
| Joint depth | 8 mm |
| Grout density | 1.6 kg/L |
| Waste allowance | 10% |
You need 2.82 kg of grout
| Result | Value |
|---|---|
| Grout | 2.8 kg |
| Joint volume (before waste) | 1.6 L |
| Grout per m² (before waste) | 0.26 kg/m² |
| Area (after openings) | 10 m² |
Show the working
- Joint volume: 10 m² × (300 + 300) ÷ (300 × 300) × 3 × 8 mm = 1.6 L
- Grout: 1.6 L × 1.6 kg/L × 1.1 (10% waste) = 2.82 kg
How it works
- 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.
Our default (adjustable)
These are typical planning figures and our own allowances, not facts about your product. Change any of them in the calculator to match your bag, pack or tin.
| 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. |