Tile Quantity Calculator

Calculate how many tiles you need for a room or wall (with waste allowance)

If you are buying tiles, the number that matters is not just the surface area. You also need to account for cutting, breakage, and awkward edges that create offcuts you cannot always reuse. This Tile Quantity Calculator is built for one practical decision: how many whole tiles you should purchase for a rectangular floor or wall using a specific tile size.

Start by entering the surface length and width in meters, then enter your tile dimensions in millimetres. The calculator converts the tile size into square meters per tile, divides your total surface area by the tile area, and then rounds up to a whole tile because you cannot buy fractions of tiles. After that it applies a waste allowance, which is the realistic buffer that stops you from running short mid-job.

In most real installations, waste is not optional. Even a clean rectangular room usually has cuts at the perimeter, around door frames, or at corners. Tiles can also chip during handling. If you want a fast but credible estimate, use the default waste allowance and only adjust it if you have a clear reason. If you know how many tiles come in a box, you can also get a box count so you can order in the same way your supplier sells them.

Assumptions and how to use this calculator

• This calculator assumes one flat rectangular surface (a simple floor or a simple wall) and does not model multiple walls, openings, niches, or complex shapes.
• Tile size is treated as the physical tile size only. Grout joint width is not used because it typically does not change the tile count enough to justify extra friction for most buyers.
• Waste allowance is applied as a percentage on top of the raw tile count. A common practical default is 10% for straightforward layouts.
• All final tile counts are rounded up to whole tiles. If you enter tiles per box, the box count is also rounded up to whole boxes.
• The calculator does not include layout patterns (for example diagonal, herringbone, or brick bond). If you use a pattern that increases cuts, increase the waste percentage.

Common questions

What waste percentage should I use?

For a basic straight lay in a normal rectangular space, 10% is a widely used rule of thumb. If the space has many corners, tight edges, or obstacles, a higher waste percentage is sensible. If you are using a pattern that creates more offcuts, increase the waste allowance rather than trying to be “perfect” with measurements.

Why does the calculator round up?

Because you cannot buy part of a tile. Even if the math says you need 72.1 tiles, you still need 73 whole tiles to complete the surface. The same logic applies to boxes: if you need 9.1 boxes, you must buy 10 boxes.

What if my room is not perfectly rectangular?

This tool is intentionally locked to a simple rectangle because that is the most common search intent and the fastest input path. If your surface is irregular, a practical workaround is to break it into rectangles, add their areas together, and enter the combined area by using an equivalent length and width (for example, keep width as 1 meter and set length equal to the total area in square meters). The key is getting a realistic total area and then keeping the waste allowance.

Do I need to include grout lines in the calculation?

Most people do not. Grout spacing changes the effective coverage slightly, but in practice the waste allowance usually covers the small differences. If you are working on a high-precision design where every millimetre matters, you are already past what a quick tile quantity calculator should try to do. In that case, measure carefully, increase your buffer, and confirm with your installer or supplier.

How do I make the estimate more accurate without adding complexity?

Use a realistic waste percentage and add a small number of spare tiles. Spares are useful for future repairs because dye lots and batches can change, meaning “the same tile” later might not match perfectly. If you know tiles per box, use that input so you order in the same units the supplier uses.