How Much Grout Do I Need? Chart by Tile Size and Joint

Grout fills the joints, so it depends on the tile size, the joint width and the tile's thickness. For 300 × 300 mm floor tiles 8 mm thick with 3 mm joints, you need about 0.29 kg of grout per m². Large tiles need far less and small tiles and mosaics far more. A 60 × 120 cm tile with 3 mm joints takes about 0.14 kg per m².

Smaller tiles mean more joints per square metre, so mosaics need far more grout than large tiles.

The formula

Grout per m² = (A + B) ÷ (A × B) × joint width × tile thickness × density, with the tile length A, width B, joint and thickness all in mm. The first part is the length of joint in one square metre; multiplying by the joint's width and depth gives litres, and the density turns litres into kilograms.

Mapei's data sheet for its Ultracolor Plus grout uses exactly this formula with a factor of 1.6. Sika gives about 1.9 kg per litre for its cement tile grout. We use 1.8 kg per litre, in the middle; if your grout's data sheet gives a figure, use that.

Grout per m² by tile size

Grout per m² (kg) by tile size and joint width, at 1.8 kg per litre, before any extra
Tile (length × width × thickness)	2 mm joint	3 mm joint	5 mm joint
100 × 100 × 7 mm	0.5 kg	0.76 kg	1.26 kg
200 × 200 × 8 mm	0.29 kg	0.43 kg	0.72 kg
300 × 300 × 8 mm	0.19 kg	0.29 kg	0.48 kg
300 × 600 × 9 mm	0.16 kg	0.24 kg	0.41 kg
600 × 600 × 10 mm	0.12 kg	0.18 kg	0.3 kg
600 × 1200 × 10 mm	0.09 kg	0.14 kg	0.23 kg

Grout per 100 sq ft

Grout per 100 sq ft (lb) by tile size and joint width
Tile	1/16 in	⅛ in	3/16 in	¼ in
4 × 4 in, ¼ in thick	7.3 lb	14.6 lb	21.9 lb	29.3 lb
6 × 6 in, 5/16 in thick	6.1 lb	12.2 lb	18.3 lb	24.4 lb
12 × 12 in, ⅜ in thick	3.7 lb	7.3 lb	11 lb	14.6 lb
12 × 24 in, ⅜ in thick	2.7 lb	5.5 lb	8.2 lb	11 lb
24 × 24 in, ⅜ in thick	1.8 lb	3.7 lb	5.5 lb	7.3 lb

Add about 10% for mixing and cleanup; the tile calculator adds it for you and counts the bags.

Worked example: a 5 × 4 m floor in 60 × 120 cm tiles

Joint length: (600 + 1200) ÷ (600 × 1200) = 0.0025 per mm, so there are 2.5 m of joint in every square metre.
Volume: 2.5 m × 3 mm wide × 10 mm deep = 0.075 litres per m², or 1.5 litres for 20 m².
Weight: 1.5 × 1.8 = 2.7 kg, or 2.97 kg with 10% extra: one 5 kg bag.

In US units: a 10 × 8 ft bathroom floor in 12 × 24 in tiles, ⅜ in thick with ⅛ in joints, takes about 4.8 lb of grout with 10% extra.

Sanded or unsanded?

Unsanded grout is for narrow joints: LATICRETE's 1600 Unsanded Grout, for example, is for joints of ⅛ in (3 mm) or less. Wider joints usually take sanded grout. The amount you need is the same either way; what changes is which product suits the joint.

Common mistakes

Leaving out the tile thickness. A joint is as deep as the tile, so a 10 mm tile takes twice the grout of a 5 mm tile with the same joint.
Mosaics. Small tiles have far more joint per square metre: 100 × 100 mm tiles take about four times the grout of 400 × 400 mm tiles.
Epoxy grout. Epoxy grouts have their own coverage charts; use the maker's figure rather than this one.