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Tile Calculator: How Many Tiles for a Room

Enter the room size, the tile size and the grout joint width. The calculator counts the tiles that fit the surface, adds a waste allowance for cuts and breakage, and converts the total into boxes.

By Adzita Editorial Team · Updated 2026-11-03 · How we build and check our tools

How the tile count is calculated

The method divides the surface area by the area one tile occupies. Each tile effectively takes up its own size plus one grout joint in each direction, so the area per tile is (tile length + joint) × (tile width + joint). The tile count is (surface area − excluded area) ÷ area per tile, rounded up, and the waste percentage is applied before rounding.

This works for floors and for walls. For a wall, enter the height as the width. For several rooms with the same tile, add up their areas first or run the calculator separately and combine the counts.

Choosing a waste allowance

Tiles are cut at walls, around pipes and at corners, and some break in handling. Ten percent is a common starting point for a straight grid. Diagonal patterns, herringbone, rooms with many corners and large-format tiles often need more, because the offcuts cannot be reused. Rectified or patterned tiles also reward a little extra, since you want to pick similar shades from one batch.

Buy all tiles for a room at once. Shade and size can vary slightly between production lots, and a later top-up may not match.

Reading box sizes

Boxes list the number of tiles and often the area they cover. Enter the tiles per box if you know it. If the box lists only an area, divide your area with waste by that figure instead. Boxes cannot be split, so the box count is always rounded up, and the leftover tiles are useful for future repairs.

What is not included

The calculator counts tiles only. Adhesive, grout, trim pieces, spacers, underlayment and waterproofing depend on the product and the substrate, so follow the manufacturer's coverage figures for those. Walls that are not square or floors with a pattern that must be centered will use more tiles than the plain area suggests. For a precise order, lay a dry row on site and count.

Layout and cutting tips

Dry-lay a row of tiles before you start so you can see how the cuts fall at the walls. Moving the starting line slightly often avoids a thin sliver of tile at one edge. Diagonal and herringbone layouts create more offcuts than straight lays, so raise the waste allowance for them. Buy all tiles from the same batch if you can, since colour and size can vary slightly between production runs, and keep a few spare tiles for future repairs.

Worked example

A 12 ft by 10 ft floor laid with 12 inch by 24 inch tiles, 3 mm joints, a 10% allowance and 8 tiles per box.

Inputs

Result

Estimating note: Quantities and ratings here are estimates for planning and learning. Products, local codes and site conditions differ, so check manufacturer data and local regulations, and use a qualified professional for electrical, structural or safety-critical work.

Frequently asked questions

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