How much grout do I need? How to use the calculator
- 1Enter the tiled area.
- 2Enter the tile size, its thickness and the joint width.
- 3Keep the density at 1.6 kg/L unless your grout bag says otherwise.
How to calculate grout (formula)
- 01Grout per m² = ((A + B) ÷ (A × B)) × C × D × density
- 02A, B = tile length and width (mm) · C = tile thickness (mm) · D = joint width (mm)
- 03Total = grout per m² × area × (1 + extra %)
(A + B) ÷ (A × B) is the length of joint in each square metre. Multiply by the joint's depth and width to get its volume in litres per m², then by the grout's density to get kilograms.
This is why 5 cm mosaics need several times more grout than 60 cm tiles: there is much more joint per square metre.
Grout calculation example
300 mm × 300 mm tiles, 8 mm thick, with 3 mm joints use 0.26 kg/m².
For 3 m × 2 m plus 10% extra, that is 1.69 kg — 1 bag of 5 kg.
How much grout per m² or per 100 ft²?
| Tile size | Joint depth | 2 mm joint | 3 mm joint | 5 mm joint | Per 100 ft², ⅛ in joint |
|---|---|---|---|---|---|
| 100 × 100 mm | 8 mm | 0.51 kg | 0.77 kg | 1.28 kg | 16.6 lb |
| 200 × 200 mm | 8 mm | 0.26 kg | 0.38 kg | 0.64 kg | 8.3 lb |
| 300 × 300 mm | 8 mm | 0.17 kg | 0.26 kg | 0.43 kg | 5.5 lb |
| 300 × 600 mm | 10 mm | 0.16 kg | 0.24 kg | 0.4 kg | 5.2 lb |
| 400 × 400 mm | 10 mm | 0.16 kg | 0.24 kg | 0.4 kg | 5.2 lb |
| 600 × 600 mm | 10 mm | 0.11 kg | 0.16 kg | 0.27 kg | 3.5 lb |
| 600 × 1200 mm | 10 mm | 0.08 kg | 0.12 kg | 0.2 kg | 2.6 lb |
| 800 × 800 mm | 10 mm | 0.08 kg | 0.12 kg | 0.2 kg | 2.6 lb |
| 12 × 12 in | 8 mm | 0.17 kg | 0.25 kg | 0.42 kg | 5.5 lb |
| 12 × 24 in | 10 mm | 0.16 kg | 0.24 kg | 0.39 kg | 5.1 lb |
| 16 × 16 in | 10 mm | 0.16 kg | 0.24 kg | 0.39 kg | 5.1 lb |
| 24 × 24 in | 10 mm | 0.1 kg | 0.16 kg | 0.26 kg | 3.4 lb |
| 24 × 48 in | 10 mm | 0.08 kg | 0.12 kg | 0.2 kg | 2.6 lb |
From the calculator's formula, (length + width) ÷ (length × width) × joint depth × joint width × 1.6 kg/L, before any spare. The joint depth is the tile thickness the calculator assumes; thicker tiles take more.
Tips before you buy
- Mix only what you can use in the working time printed on the bag.
- Use the same grout batch for the whole job to keep the colour even.
- Epoxy grout has a different density and coverage — use the manufacturer's chart.
Frequently asked questions
How much grout do I need per m²?
For 30 × 30 cm tiles with 3 mm joints it's only about 0.25 kg/m². For 5 × 5 cm mosaics it can be 0.5–1 kg/m² or more.
Does tile thickness matter?
Yes — the joint is filled to the full tile thickness, so thicker tiles need proportionally more grout.
Sources
- Method: joint volume × density, the relationship used in grout manufacturers' consumption calculators.
- Pack sizes: the usual shop sizes — 1 kg packets in Pakistan and India, 2–20 kg in Europe, 10 lb and 25 lb bags in the US. Pick yours or enter its weight.
Formulas last reviewed: September 30, 2026 ·How we check our formulas