How much grout do I need per square metre?

It depends on the tile size, joint width and tile thickness. Small tiles (100x100 mm) with 3 mm joints need approximately 1.5-2.0 kg/m². Large tiles (600x600 mm) with 3 mm joints need only about 0.3-0.5 kg/m². Wider joints dramatically increase consumption — doubling the joint width roughly doubles the grout needed. Natural stone with wide joints (5-10 mm) can use 2-5+ kg/m².

What width grout joint should I use?

For rectified (precision cut) porcelain tiles, joints as narrow as 1.5-2 mm are possible. For standard ceramic wall tiles, 2-3 mm is typical. For floor tiles, 3-5 mm is standard. For natural stone, 5-10 mm is common. Very large format tiles often use 2-3 mm joints. Always follow the tile manufacturer recommendation — joints too narrow can crack, and some tiles require wider joints to accommodate size variation.

What is the difference between sanded and unsanded grout?

Sanded grout contains fine sand and is used for joints 3 mm and wider — the sand provides bulk and prevents cracking in wider joints. Unsanded grout is smoother and used for joints under 3 mm and for polished or scratch-sensitive tiles (marble, polished porcelain). Epoxy grout is stain-proof and waterproof but more expensive and harder to work — ideal for wet areas, commercial kitchens and areas needing chemical resistance.

How do I calculate grout quantity?

Formula: kg/m² = (joint width x tile depth x (tile length + tile width)) / (tile length x tile width) x grout density (typically ~1.6 kg/litre). All measurements in mm, result in kg/m². For example: 300x300 mm tiles, 8 mm thick, 3 mm joints = (3 x 8 x 600) / (300 x 300) x 1.6 = 0.26 kg/m². Add 10-15% for waste.

UK Grout Coverage Rates by Tile Size

Grout quantities in kg/m² by tile size and joint width, from 100x100 mm mosaics to 600x600 mm large format tiles.

Grout Coverage Table (kg/m²)

Based on 8 mm tile thickness and grout density ~1.6 kg/litre. Values are approximate — add 10-15% for waste.

Tile Size (mm)	2 mm joint	3 mm joint	5 mm joint	10 mm joint
100 x 100	0.51	0.77	1.28	2.56
150 x 150	0.34	0.51	0.85	1.71
200 x 200	0.26	0.38	0.64	1.28
250 x 250	0.20	0.31	0.51	1.02
300 x 300	0.17	0.26	0.43	0.85
300 x 600	0.13	0.19	0.32	0.64
400 x 400	0.13	0.19	0.32	0.64
450 x 450	0.11	0.17	0.28	0.57
500 x 500	0.10	0.15	0.26	0.51
600 x 600	0.09	0.13	0.21	0.43

Grout Types

Type	Joint Width	Key Properties	Best For
Unsanded cementitious	1–3 mm	Smooth finish, non-scratching	Polished tiles, narrow joints, walls
Sanded cementitious	3–15 mm	Strong, bulk fill, textured	Floors, wide joints, natural stone
Flexible cementitious	2–10 mm	Movement accommodation	UFH, timber substrates, large tiles
Epoxy	1–15 mm	Stain-proof, waterproof, chemical resistant	Wet rooms, commercial kitchens, pools
Resin	1–6 mm	Flexible, water-resistant	Bathrooms, splashbacks

Coverage Per Bag

Bag Size	300x300 tiles, 3 mm joints	600x600 tiles, 3 mm joints
2.5 kg	~9 m²	~19 m²
5 kg	~19 m²	~38 m²
10 kg	~38 m²	~77 m²

Related Calculators

See the Tile Adhesive Coverage for adhesive quantities, or the Floor Tile Calculator for tile quantities.

How We Calculate This

Frequently Asked Questions

Last updated: April 2026

All calculations are estimates. Verify with your supplier.

UK Grout Coverage Rates by Tile Size

Grout Coverage Table (kg/m²)

Grout Types

Coverage Per Bag

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How We Calculate This

Frequently Asked Questions

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