Tile Quantity Calculator for Floors and Walls

How the calculation works

How to calculate the number of tiles you need

Running short of tile is one of the most common and costly problems in a tiling job. A tile line can be discontinued or sold out, and tiles from different production batches can show visible differences in shade. Calculating the quantity properly before the first order is therefore a practical decision with real consequences for the finished room.

The formula and what it leaves out

The basic logic is simple: divide the area to tile by the area of one tile, then round up. A bathroom measuring 2 m × 3 m (about 6.6 ft × 9.8 ft, or about 65 sq ft) has 6 m² of floor to cover. With 30 × 60 cm tiles at 0.18 m² each, that is 6 ÷ 0.18 = 33.3, so 34 tiles before any allowance.

The problem is the cuts. A tiled area is never covered without cutting pieces: at the corners, along the floor, around outlets, shower valves, drain covers and access panels. Each cut leaves an offcut, and offcuts are often hard to reuse, so every cut costs material. The waste allowance exists to cover those cuts, accidental breakage during installation and a small reserve for repairs later.

The calculator applies the allowance as a percentage of the total area before dividing by the area of one tile. For a straight lay in the same bathroom, 6 m² × 1.10 ÷ 0.18 = 36.7, which rounds up to 37 tiles. Buying 40 leaves a few spares for future repairs, which is often worth the small extra cost.

The waste percentages used in the examples are planning assumptions, not fixed rules. EN 14411, the European reference standard for ceramic tiles, classifies properties such as water absorption and dimensions, but it does not set a waste allowance for a job. That decision rests with the person doing the installation. In Canada, the National Building Code of Canada is a model code that each province and territory adopts and amends, so local authorities may add requirements for a specific project. For North American tile specifications, ANSI A137.1 is the reference to check against the product data sheet.

Common tile sizes and what they mean for quantities

The tile format changes both the number of pieces and the look of the finished surface. These are the sizes most often sold for home projects:

• 20 × 20 cm (about 8 × 8 in, 0.04 m² per tile, 25 tiles per m²): a classic size for bathroom walls and traditional kitchens.
• 30 × 60 cm (about 12 × 24 in, 0.18 m² per tile, about 5.6 tiles per m²): a widely used mid-size format that balances cutting and appearance.
• 60 × 60 cm (about 24 × 24 in, 0.36 m² per tile, about 2.8 tiles per m²): a common floor size in basements, entrances and open-plan kitchens.
• 60 × 120 cm (about 24 × 48 in, 0.72 m² per tile, about 1.4 tiles per m²): a large format that has grown in popularity because it has fewer grout lines.

Larger tiles mean fewer grout lines, which makes cleaning easier, a useful point for bathrooms and kitchens. They also place more demands on the substrate. A small unevenness in the floor is far more visible across a large tile, so check the flatness requirement in the data sheet for the product you have chosen and ask the installer whether the subfloor needs levelling before the tile goes down.

Choosing the layout

After the tile size, the layout is the biggest factor in the quantity. A straight lay, with the joints parallel to the walls, produces the fewest cuts. A diagonal lay at 45 degrees produces many more triangular cuts, and each one wastes material. That is why a diagonal lay needs a larger allowance than a straight one.

Herringbone and other complex patterns need a larger allowance again, because the cuts are frequent and the pieces are awkward to reuse. Mixing two formats in the same area adds the same problem, since the leftovers from one size rarely fit the other. In these cases, plan the layout on paper before ordering, and order more than the calculator suggests for a simple lay.

Measuring the area correctly

Measure wall to wall and floor to floor, including the areas behind a toilet, above a vanity or along a short return wall. A common mistake is to forget the strip of wall above a suspended ceiling, which still needs tile if it is part of the visible surface.

Openings are the other question. In a bathroom or a small kitchen, it is generally not worth deducting doors and windows, because the cuts around them use up enough material to offset the uncovered area. Only large openings, such as a wide garage door, justify a deduction. When in doubt, leave the opening in the total, since ordering a little extra is safer than running short. Small windows and niches should always stay in the total.

Common mistakes

Buying the exact amount with no allowance is the most common error and the most expensive to correct. A product can be discontinued, change batch or sell out between the first purchase and the moment a repair is needed. Keeping a few spare tiles usually costs less than a second trip to find a matching batch.

The second common error is using the straight-lay allowance for a diagonal job. The shortfall is often small, but the box needed to close it may no longer exist in the same batch.

The third is ignoring the box count. The number of pieces per box depends on the format, and the box label states it. The calculator gives a total number of tiles, so the last step is to divide by the pieces per box and round up to a whole box.

Materials beyond the tile

The calculator covers the tile only. A complete job also needs tile adhesive, grout, sealant and spacers, and each has its own quantity. Adhesive and grout are sold by bag, and the manufacturer's data sheet gives the coverage for each. In wet areas such as showers, check whether the substrate needs a waterproofing membrane before tiling, since that layer is normally specified separately from the tile.

Cost estimate

If you enter a price per square metre, the calculator shows an estimate of the material cost based on the quantity and that price. Use the price quoted by your supplier, and check whether it includes tax. The estimate covers the tile only. It leaves out delivery, adhesive, grout, underlayment and labour.

When to ask a tile installer

For a standard bathroom wall or a plain floor, the calculator is enough. Before ordering, consult an experienced installer if you plan a herringbone or other complex pattern, combine two formats in one area, or have an irregular layout with columns, curved niches or vanity cut-outs. A good installer can plan the cuts to reduce waste, which matters most with expensive tile, where each piece carries real weight in the budget.

For questions about tile performance and classification, consult EN 14411 and ANSI A137.1, and your local building department for any additional requirements that apply to your project.