Tile and Flooring Quantity Calculator
How the formula works
To buy the right number of tiles, you need the area of the floor, the size of one tile with its grout joint, and an allowance for cuts and breakage. This calculator finds the number of tiles and boxes, and it also estimates the adhesive and the grout. It can work the other way too, and tell you how much area a given number of tiles will cover.
Step 1: Floor area
Area of one room = Length × Width
Total area = Area of one room × Number of rooms − Area to deduct
Step 2: Number of tiles
Tile area with joint = (Tile length + Joint) × (Tile width + Joint)
Tiles needed = Total area ÷ Tile area with joint (rounded up)
Tiles with wastage = Tiles needed × (1 + Wastage %) (rounded up)
Boxes = Tiles with wastage ÷ Tiles per box (rounded up)
Step 3: Adhesive and grout
Adhesive (kg) = Total area × 1.5 kg per m² per mm of bed thickness × Bed thickness (mm)
Grout (kg per m²) = 1.6 × J × T × (L + W) ÷ (L × W)
Grout (kg) = Grout per m² × Total area
Area covered by tiles
Area covered = Number of tiles × Tile area with joint
Where
- L and W = tile length and width in mm
- T = tile thickness in mm
- J = grout joint width in mm
- 1.6 = density of grout in kg per litre
Typical wastage
- 5 % for a straight layout in a simple, rectangular room
- 10 % for a typical room with some cuts
- 15 % for a diagonal layout or a pattern
- 20 % for a complex layout, many corners, or large format tiles
How to use the calculator
- Select the calculation and the unit system.
- Enter the room length and width, or the floor area, and the number of rooms. Enter any area to deduct.
- Select the tile size, the grout joint width, the wastage and the tile thickness.
- Enter the tiles per box, the adhesive bed and the price if you want boxes, adhesive and cost.
- Click Calculate. You can then download the result as a PDF.
Important notes
- The result is an estimate. Adhesive and grout use changes with the tile, the surface and the product, so check the data sheet.
- Buy all the tiles from the same batch, because the colour and the size can differ between batches.
- Keep a few extra tiles for repairs in the future.
Worked example
Example 1: Room with 600 x 600 mm tiles
A room is 5 m × 4 m. Use 600 × 600 mm tiles with a 3 mm joint, 10 % wastage, 10 mm tile thickness, a 5 mm adhesive bed, 4 tiles per box and a price of 60 per tile.
Step 1: Area
5 × 4 = 20 m² (215.28 ft²)
Step 2: Tiles
Tile area with joint = 0.603 × 0.603 = 0.3636 m²
Tiles needed = 20 ÷ 0.3636 = 55.0, rounded up to 56 tiles
Tiles with 10 % wastage = 55.0 × 1.10 = 60.5, rounded up to 61 tiles
Boxes = 61 ÷ 4 = 15.25, so buy 16 boxes (64 tiles, 23.04 m² of tile)
Step 3: Adhesive and grout
Adhesive = 20 × 1.5 × 5 = 150 kg, which is 8 bags of 20 kg
Grout per m² = 1.6 × 3 × 10 × (600 + 600) ÷ (600 × 600) = 0.16 kg, so the grout is 20 × 0.16 = 3.2 kg
Step 4: Cost
64 tiles × 60 = 3,840
Example 2: Room in feet
A room is 12 ft × 10 ft (120 ft², 11.15 m²). Use 300 × 300 mm tiles with a 2 mm joint, 10 % wastage, 8 mm thickness and a 3 mm adhesive bed.
Tile area with joint = 0.302 × 0.302 = 0.0912 m²
Tiles needed = 11.15 ÷ 0.0912 = 122.2, rounded up to 123 tiles
Tiles with 10 % wastage = 135 tiles (12.15 m² of tile)
Adhesive = 11.15 × 1.5 × 3 = about 50 kg (3 bags of 20 kg)
Grout = about 1.9 kg
Example 3: Known area with a deduction
A hall has a floor area of 45 m² and 2 m² of it is covered by fixed units. Use 800 × 800 mm tiles with a 2 mm joint, 15 % wastage, 10 mm thickness, 3 tiles per box and a price of 850 per tile.
Total area = 45 − 2 = 43 m²
Tile area with joint = 0.802 × 0.802 = 0.6432 m²
Tiles needed = 43 ÷ 0.6432 = 66.9, rounded up to 67 tiles
Tiles with 15 % wastage = 77 tiles
Boxes = 77 ÷ 3 = 25.7, so buy 26 boxes (78 tiles, 49.92 m² of tile)
Grout = about 3.4 kg
Cost = 78 × 850 = 66,300
Example 4: Area covered by a number of tiles
You have 150 tiles of 600 × 600 mm and you plan a 3 mm joint.
Area covered = 150 × 0.603 × 0.603 = 54.54 m² (587.08 ft²). This is about 2.75 tiles per m².
Common mistakes
- Ignoring the wastage. Cuts at the walls, broken tiles and mistakes need extra tiles. Always add a wastage allowance.
- Forgetting the grout joint. The tile and the joint together cover the floor. A joint of 3 mm on a 300 mm tile changes the count by about 2 %.
- Mixing units. Room sizes may be in metres or feet and tile sizes in millimetres or inches. Select the right units before you enter the numbers.
- Not deducting fixed items. Fixed cabinets, bathtubs and steps are not tiled. Deduct their area, but keep in mind that tiles must still be cut around them.
- Rounding down. Always round the tiles and the boxes up. You cannot buy part of a tile or a box.
- Using the same wastage for every layout. A diagonal or pattern layout needs more tiles than a straight layout.
- Mixing batches. Tiles from different batches can show a different colour or size. Buy the full quantity at the same time.
- Using the same adhesive for every tile. Large tiles need a thicker bed and a suitable adhesive. Follow the data sheet.
- Forgetting uneven floors. A rough or uneven base uses more adhesive. Level the floor first.
Frequently asked questions
How do I calculate the number of tiles for a floor?
Divide the floor area by the area of one tile, including its joint, then add a wastage allowance. For a 20 m² room with 600 × 600 mm tiles and a 3 mm joint, you need about 56 tiles, or 61 tiles with 10 % wastage.
How much extra should I buy for wastage?
Buy about 5 % extra for a straight layout, 10 % for a typical room, 15 % for diagonal or pattern layouts, and up to 20 % for complex rooms or large tiles.
How do I find the number of tiles per square metre?
Divide 1 by the area of one tile with its joint in m². For a 600 × 600 mm tile with a 3 mm joint, that is about 2.75 tiles per m².
How many boxes of tiles do I need?
Divide the tiles with wastage by the number of tiles in one box and round up. For 61 tiles with 4 tiles per box, you need 16 boxes.
How much tile adhesive do I need?
A common estimate is about 1.5 kg per m² for each mm of bed thickness. A 5 mm bed over 20 m² needs about 150 kg. Check the data sheet of your adhesive.
How much grout do I need?
The grout depends on the tile size, the thickness and the joint width. The calculator uses the formula 1.6 × J × T × (L + W) ÷ (L × W) in kg per m². A 600 × 600 mm tile, 10 mm thick with a 3 mm joint needs about 0.16 kg per m².
What joint width should I use?
Many floor tiles use 2 to 3 mm. Rectified tiles can use 1.5 to 2 mm, and rough or large tiles can use 5 mm. Follow the tile maker’s advice.
How do I convert tile sizes from inches to millimetres?
Multiply inches by 25.4. A tile of 12 × 12 inches is about 305 × 305 mm, and 24 × 24 inches is about 610 × 610 mm. The calculator accepts inches in the custom size option.
Can I calculate the tiles for more than one room?
Yes. Enter the number of identical rooms. For rooms with different sizes, calculate each one, or add the areas and enter the total as a known area.
Can I use this for wood plank or vinyl flooring?
Yes, for the number of planks, you can enter the plank size as a custom size and set the joint to 0. Check the box coverage on the pack for the exact count.
Does the calculator include the cost?
Yes, if you enter the price per tile. The cost is for the tiles you buy, which means whole boxes if you give the tiles per box.