Tile and grout calculator — tiles, grout and adhesive
A 4×3 m room in 60×60 tiles needs 37 tiles, 1.15 kg of grout, 3 bags of adhesive and 9 backer boards at 10% waste. Type your room and tile size below and get the full list for any room — free, no signup.
Your quantities
How the tiles and grout are worked out
Tiles: the room's area is divided by one tile's area, your waste percentage is added, and the count is rounded up — cuts and breakages are part of tiling, so the waste is added before rounding, never after.
Grout: the calculator works out the total joint volume from the tile size, joint width and joint depth, then converts it to a weight of grout powder. Adhesive bags assume one 20 kg bag covers about 4.6 m², and each backer board covers about 1.4 m².
Running these jobs? Tiling & Flooring
How to use the tile and grout calculator
- Measure the room: length × width, in metres or feet.
- Choose the tile size and set the joint width and depth — 3 mm joints are the floor standard.
- Set the waste: 10% for a straight layout, 15% for diagonal or herringbone.
- Read the shopping list: tiles, grout powder, adhesive bags and backer boards.
How many tiles and how much grout for a 4×3 m room?
The room is 12 m² and each 60×60 tile covers 0.36 m², so 34 tiles cover it exactly; 10% waste for cuts and breakage brings the order to 37 tiles.
The 3 mm joints at 6 mm deep hold 1.15 kg of grout powder. The same room also takes 3 bags of adhesive — one 20 kg bag covers about 4.6 m² — and 9 backer boards at about 1.4 m² per board.
Tile sizes and coverages the calculator uses
Tile sizes — coverage per tile
| Tile size | Area per tile | Tiles per m² (before waste) |
|---|---|---|
| 15 × 15 cm | 0.0225 m² | 44.4 |
| 30 × 30 cm | 0.09 m² | 11.1 |
| 60 × 60 cm | 0.36 m² | 2.78 |
Adhesive and backer board coverage
| Material | Coverage |
|---|---|
| Tile adhesive, 20 kg bag | About 4.6 m² per bag |
| Cement backer board, 3 × 5 ft sheet | About 1.4 m² per sheet |
Tiling tips that save a second trip
- Order tiles from one batch: dye lots differ slightly between batches, and a shortfall topped up later can show on the floor.
- Small tiles drink grout — in 15 cm tiles with 6 mm joints the 4×3 m room needs 9.22 kg of grout, eight times the 60 cm figure. Check the grout line before you order, not after.
- Keep a few spare tiles from the same batch after the job; a cracked tile years later is an easy repair only if the tile still exists.
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How many 60×60 tiles do I need for a 4×3 m room?+
37 tiles with 10% waste. The room is 12 m², each tile covers 0.36 m², so 34 tiles cover it exactly — waste for cuts and breakage brings the order to 37.
How much grout does a tiled room need?+
It depends on the joints: wider and deeper joints drink far more. For the 4×3 m room above with 60 cm tiles and 3 mm joints, about 1.15 kg of grout powder. Small tiles with wide joints can need eight times that.
How many bags of tile adhesive cover a room?+
One 20 kg bag covers about 4.6 m² at a standard bed. The 12 m² room above needs 3 bags — order by the calculator, not by the old habit of one bag per room, which runs short on any real floor.
How many tiles do I need per square metre?+
It is the tile’s area turned upside down: a 60×60 tile covers 0.36 m², so a square metre takes 2.78 tiles before waste; a 30×30 covers 0.09 m² and takes 11.1. The calculator rounds the whole room up in one go, waste included.
How much waste should I add for tiles?+
10% for a straight layout in a square room, and 15% for diagonal or herringbone patterns, corners and edge trims. The waste is added before the tile count is rounded up, so cuts and breakage are already covered.
How many backer boards do I need?+
One cement backer board covers about 1.4 m² — a standard 3 × 5 ft sheet. The 12 m² room above therefore needs 9 boards. Divide your floor area by 1.4 and round up for a quick check.
Should I use sanded or unsanded grout?+
Sanded grout — cement with fine sand — suits joints from 3 to 13 mm. Unsanded grout is a smooth cement paste for joints under 3 mm, where sand would scratch polished marble or glass tiles.
How does the joint change the grout weight?+
Grout fills the joints, so wider joints, deeper joints and smaller tiles all push the weight up. The 4×3 m room needs 1.15 kg with 60 cm tiles and 3 mm joints — in 15 cm tiles with 6 mm joints the same room needs 9.22 kg.
How is grout weight calculated?+
From the total joint volume: the calculator adds up the length of every joint from the tile size, multiplies by the joint width and depth, and converts that volume into a weight of grout powder. That is why tile size changes the answer as much as room size does.
When can I grout after laying the tiles?+
Wait 24 hours after setting with standard polymer-modified adhesive. Grouting too early traps movement under the tiles and weakens both the bed and the joints.
Can I tile over existing tiles?+
Yes, if the old tiles are sound and firmly bonded. Clean them, degloss the surface by grinding, and prime with a bonding primer before setting the new tiles in modified adhesive.
What does this calculator not include?+
No prices and no labour — quantities only. It also does not count skirting, edge trim or threshold pieces, so add those separately if the job needs them. The quantities do not carry into InstaJack automatically yet.