Tile calculator — how many tiles do I need?
Turn floor and wall measurements into a tile count and a number of boxes, allowing for grout joints and cutting waste.
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- Nothing you enter is sent
- Free, no account
Area
48 sq ft
Area
42 sq ft
Measured area
90 sq ft
With 10% waste
99 sq ft
In square metres
9.2 m²
In square yards
11 sq yd
Estimated cost
$0.00
enter a price to see this
| Area | Shape | Dimensions | Sq ft |
|---|---|---|---|
| Bathroom floor | Rectangle | 8' 0" × 6' 0" | 48 |
| Shower wall | Single wall | 3' 0" × 7' 0" | 42 |
Formula and working
Area of each shape
Rectangle: length × width · Single wall: width × height Bathroom floor: 8.00 × 6.00 ft = 48.00 sq ft Shower wall: 3.00 × 7.00 ft × 2 = 42.00 sq ft = 90 sq ft total
Effective tile size
tile area = (width + grout) × (height + grout) ÷ 144 = 12.125 × 12.125 ÷ 144 = 1.0209 sq ft = 1.0209 sq ft per tile
Tiles required
tiles = area × (1 + waste) ÷ tile area, rounded up = 90.00 × 1.10 ÷ 1.0209 = 97 tiles · 10 boxes
Metric conversion
1 sq ft = 0.09290304 m² exactly (1 ft = 0.3048 m) 90.00 × 0.09290304 = 8.361 m²
Feet-and-inches entries such as 12′ 6″ are read exactly, and the conversion to metres uses the international foot of 0.3048 m, which is exact by definition.
Assumptions
- Measure the longest and widest points of each space, and split awkward rooms into two rectangles rather than trying to describe them with one shape.
- Waste allowance covers off-cuts, breakages and mistakes. Ten per cent is the usual figure; go to fifteen for diagonal layouts, herringbone patterns or a room with many angles.
- Tile counts assume a straight grid layout with the grout joint added to each tile. Diagonal, herringbone and brick-bond layouts cut more tiles and need a bigger allowance.
- Square footage is a plan area. It does not account for skirting, thresholds, or the direction a plank or tile will run.
- Nothing is uploaded. Saving is off by default and writes only to this browser, with a delete button next to the switch.
Tiles are counted, not measured
The area tells you how much surface there is; the tile count tells you what to buy, and the two are separated by the grout joint and the waste allowance.
effective tile area = (width + joint) × (height + joint) ÷ 144 [sq ft]
tiles needed = area × (1 + waste) ÷ effective tile area, rounded up
boxes = tiles ÷ tiles per box, rounded upA 12 × 12 inch tile with a 1/8 inch joint effectively occupies 12.125 × 12.125 inches, or 1.0209 square feet. A hundred square feet therefore needs 98 tiles before waste, not 100 — and 108 with a 10% allowance.
Grout joints matter most on small tiles
| Tile size | Joint | Area taken by grout | Tiles per 100 sq ft |
|---|---|---|---|
| 2 × 2 in mosaic | 1/8" | 11.4% | 3,189 |
| 4 × 4 in | 1/8" | 6.0% | 846 |
| 6 × 6 in | 1/8" | 4.0% | 384 |
| 12 × 12 in | 1/8" | 2.1% | 98 |
| 12 × 24 in | 1/16" | 0.8% | 50 |
| 24 × 24 in | 1/16" | 0.5% | 25 |
Common joints as decimals: 1/16" = 0.0625, 1/8" = 0.125, 3/16" = 0.1875, 1/4" = 0.25.
On a large-format floor the joint barely registers. On mosaic it removes more than a tenth of the coverage, which is exactly the size of the error that leaves you two sheets short on a Sunday.
How much waste to allow
- 10% — straight grid layout, simple rectangular room.
- 15% — diagonal, herringbone or brick-bond layouts, which cut far more tiles.
- 15–20% — rooms with many angles, niches, alcoves or curved edges.
- + a few spares — beyond the percentage, keep whole tiles for future repairs.
The waste figure is not padding. It is off-cuts you genuinely cannot reuse, tiles that break during cutting, and the pieces at the room edge where less than half a tile is left.
Buy from one batch
Ceramic and porcelain tiles are produced in batches, and colour and size vary measurably between them — most manufacturers print a batch or "shade" code on the box precisely because of this. Ordering a second box a month later frequently produces a visible band across the floor. Buy the whole quantity including waste in one order, and keep the leftovers.
Floors and walls in one job
Add a row per surface. Use the rectangle shape for a floor and the wall shape for vertical areas, and set a quantity where several identical walls repeat — three shower walls at 3 × 7 ft is one row with a quantity of three. The totals cover the whole job, so the box count you take to the merchant is for everything at once.
There is no negative-area row, and there does not need to be: measure the tiled surface directly. A shower wall with a window in it is far easier described as two rectangles than as one rectangle minus a hole.
The other materials
This calculator counts tiles. The rest of the job scales with the same area, roughly:
- Adhesive — around 4–6 kg per m² (roughly 1 lb per sq ft) for a notched trowel on a flat floor, more for large-format tiles that need back-buttering.
- Grout — depends on tile size, joint width and depth. Manufacturers publish a coverage chart; small tiles with wide joints use several times more than large-format.
- Spacers, trim and edging — counted by the perimeter, not the area.
Metric tiles
European tiles are sold in millimetres — 300 × 300, 600 × 300, 600 × 600 are the common sizes. Convert to inches (divide by 25.4) for the tile dimension fields, or measure the room in metres and read the square-metre total, which is what a European merchant will quote against. 300 mm is 11.81 in; 600 mm is 23.62 in.
No upload, works in an empty room
Everything runs in your browser. There is no server, no account and no network request, so the page keeps working in a half-renovated bathroom with no signal. Your measurement list is stored only if you turn saving on, and only on this device.
Questions
How many tiles do I need per square foot?
Divide by the tile’s area including its grout joint. A 12 × 12 inch tile with a 1/8 inch joint effectively covers 12.125 × 12.125 inches, or 1.02 square feet — so a hundred square feet needs about 98 tiles before waste.
Does the grout joint really matter?
For small mosaic tiles, yes — a 1/8 inch joint around a 2 inch tile is over 12% of the area. For large-format tiles the effect is small but it still shifts the box count at the margin, which is where you run out.
How much extra should I buy?
Ten per cent for a straight grid layout, fifteen for diagonal or herringbone, and more for a room with many angles or niches. Buy the overage in the same batch — dye lots differ visibly between production runs.
Can I mix floors and walls in one job?
Yes. Add a row per surface, use the wall shape for vertical areas, and set a quantity for repeated identical walls. The totals cover the whole job.