Floor Tile Calculator – Room & Wall Coverage

Calculate Floor and Skirting Tile Quantity

Floor Tile Estimation Formula

Formula

\[ P = 2(L + W) - D \\ A_{\text{skirting}} = \frac{P \cdot Sh}{1\,000\,000} \\ A_{\text{floor}} = \frac{L \cdot W}{1\,000\,000} \\ A_{\text{total}} = A_{\text{floor}} + A_{\text{skirting}} \\ A_{\text{tile}} = \frac{Tl \cdot Tw}{1\,000\,000} \\ N = \left\lceil \frac{A_{\text{total}}}{A_{\text{tile}}} \cdot \left(1 + \frac{W\%}{100}\right) \right\rceil \]

Where:

\(L\) — room length (mm)
\(W\) — room width (mm)
\(Tl\) — tile length (mm)
\(Tw\) — tile width (mm)
\(Sh\) — skirting height (mm)
\(D\) — door width, the wall section with no skirting (mm)
\(W\%\) — wastage allowance for cuts and breakage (%)
\(N\) — number of tiles, rounded up to the next whole tile

The formula divides all millimetre dimensions by 1,000,000 to work in square metres, adds the skirting area to the floor area, and applies the wastage factor before rounding up to a whole number of tiles.

Floor Tile Estimator – Calculation Example

Example: a rectangular room is 5000 mm long and 4000 mm wide. The tiles are 600 mm × 600 mm, the skirting is 100 mm high, the doorway is 800 mm wide, and a 5% wastage allowance is applied.

\[ P = 2(5000 + 4000) - 800 = 17\,200 \text{ mm} \]

\[ A_{\text{skirting}} = \frac{17\,200 \times 100}{1\,000\,000} = 1.72 \text{ m}^2 \]

\[ A_{\text{floor}} = \frac{5000 \times 4000}{1\,000\,000} = 20 \text{ m}^2 \]

\[ A_{\text{total}} = 20 + 1.72 = 21.72 \text{ m}^2 \qquad A_{\text{tile}} = \frac{600 \times 600}{1\,000\,000} = 0.36 \text{ m}^2 \]

\[ N = \left\lceil \frac{21.72}{0.36} \times 1.05 \right\rceil = \lceil 63.35 \rceil = 64 \]

Result: you need 64 tiles (600 mm × 600 mm) to cover the floor and skirting with 5% wastage included.

How to use the calculator

Enter the Room length and Room width in millimetres — measure the longest and widest points of the floor.
Enter the Tile length and Tile width in millimetres as stated on the tile packaging.
Set the Skirting height — the height of the tiled border running along the walls, typically 75–150 mm.
Enter the Door width, so the calculator subtracts the wall section where no skirting is needed.
Set the Tile wastage percentage — 5% is a common default; use 10% or more for diagonal layouts or small rooms with many obstacles.
Read the Number of tiles in the result field. The value is always rounded up, because you cannot buy a fraction of a tile.

What the Floor Tile Estimator does

Planning a tiling project starts with one deceptively simple question: how many tiles do I buy? Underestimating means a second delivery, possible batch-colour mismatches and delays; overestimating means paying for boxes you will never open. This estimator answers the question by combining two coverage areas that are usually ordered together: the floor and the skirting (the tiled strip along the base of the walls).

The calculation works in three stages. First, it finds the floor area from the room length and width. Second, it finds the skirting area by multiplying the room perimeter — reduced by the door width, since no skirting is laid across a doorway — by the skirting height. Third, it converts both areas to square metres, divides the total by the area of a single tile, applies your wastage percentage, and rounds up to a whole tile.

The result is best read as a minimum purchase quantity. It assumes the tile area is fully usable, including offcuts produced during cutting. Because tiles are sold by the box, check how many tiles a box contains and round your purchase up to the next full box — keeping a few spares is wise for future repairs.

The same logic applies to outdoor surfaces: if you are paving a patio or path instead of tiling a room, our Paving Stones Calculator handles that case.

Assumptions, limitations and practical tips

Rectangular rooms only. The formula uses length × width, so L-shaped or irregular rooms should be split into rectangles, calculated separately and summed.
Door width is subtracted once. If the room has several doorways or openings below skirting height, add their widths together and enter the total as the door width.
Wastage covers cuts and breakage, not layout patterns. Diagonal (45°) layouts, herringbone patterns or rooms with many columns and pipe penetrations generate far more offcuts — raise the wastage to 10–15%.
Grout joints are ignored. For large-format tiles with narrow joints this has little effect; for very small tiles the joint width slightly reduces the effective number of tiles needed, giving a small safety margin.
Check tile availability before ordering. Confirm the tile size in millimetres rather than nominal inches, and buy all tiles from the same batch number to avoid shade variation.
Budget for the bedding material too. Once you know the area, the Cement and Sand for Plastering Calculator can help you estimate mortar quantities for the tile bed, and the Concrete Slab Pour Volume Calculator is useful if a new screed is part of the project.

Frequently Asked Questions

How do I calculate the number of floor tiles by hand?

Multiply room length by width to get the floor area, then add the skirting area: the wall perimeter (minus door width) times the skirting height. Divide the total by one tile's area and round up. For example, a 4 m × 3 m room with 600 mm × 600 mm tiles needs \(12 \div 0.36 = 34\) tiles before adding wastage. In square metres: \(A_{\text{tile}} = \frac{Tl \times Tw}{1\,000\,000}\).

What wastage percentage should I use for tiles?

5% is standard for a straight (parallel) layout in a simple rectangular room. Use 10% if the room has many corners, pipes or columns, and 10–15% for diagonal or herringbone patterns, which produce far more offcuts. Very small rooms with large tiles also warrant the higher figure. Wastage covers cuts and breakage only — it does not replace buying a few spares for future repairs.

Can I enter dimensions in centimetres, inches or feet instead of millimetres?

The calculator expects millimetres, so convert first: 1 cm = 10 mm, 1 inch = 25.4 mm, 1 foot = 304.8 mm. For example, a 16-inch tile is 406 mm, and a 12-foot wall is 3658 mm. If you prefer working in metres, multiply by 1000 for each dimension. Mixing units is the most common source of wildly wrong tile counts.

How do I calculate tiles for an L-shaped or irregular room?

Split the floor into rectangles, calculate each rectangle separately, and add the areas together before dividing by the tile area. For the skirting, measure the actual wall lengths rather than relying on the rectangle perimeter formula. Alternatively, run the calculator once per rectangle and sum the results — but apply the wastage and round-up to the combined total, not to each part separately.

How many boxes of tiles should I buy?

Tiles are sold by the box, so divide the calculator's tile count by the number of tiles per box and round up to the next whole box. For example, 64 tiles at 8 per box means buying 8 boxes (64 tiles exactly), but 65 tiles means 9 boxes. Check the box count on the packaging — it varies by manufacturer and tile size — and always buy from the same batch number to avoid shade differences.

Why is my tile count higher than the shop's estimate?

Most shop estimates cover only the plain floor area, while this calculator adds skirting and applies wastage on top. Also confirm you entered the true tile size in millimetres, not a nominal size — a '12 inch' tile is often actually 305 mm or slightly less. Finally, check that the wastage percentage and door width were entered correctly; a missing door subtraction inflates the skirting area.

Does the calculator account for grout joints and adhesive?

No — grout joints are ignored, which for narrow 2–3 mm joints with large tiles has little effect and even gives a small safety margin. For very small mosaic-style tiles, joints slightly reduce the number of tiles needed, so the result stays conservative. Adhesive and bedding material must be budgeted separately: once you know the total area in square metres, use our cement and sand calculators to estimate those quantities.