Tile Calculator

How to use this calculator

Measure the floor or wall area to be tiled and enter it, then enter the tile's length and width. The tile area is calculated for you; you can also type a tile area directly if you are working from a box label that lists "ft² per tile". The waste allowance defaults to 10%, the usual figure for straight layouts in a rectangular room.

Increase the waste allowance to 15% for diagonal layouts, herringbone or rooms with many corners, and to 20% for large-format tiles or natural stone that varies in color. The calculator also works in reverse: enter how many tiles you have to see the area they will cover. Grout joints are ignored because they reduce tile count only slightly, which acts as an extra safety margin.

The formula

a = l × w

N = (A / a) × (1 + waste)

A: area to tile
l: tile length
w: tile width
a: area of one tile
w%: waste allowance
N: tiles needed

Worked example

A 10 × 10 ft bathroom floor will be laid with 12 × 12 in tiles in a straight pattern.

Tile area = 12 × 12 = 144 in² = 1 ft².
Tiles without waste = 100 ft² ÷ 1 ft² = 100.
With 10% waste: 100 × 1.10 = 110 tiles.

Order 110 tiles — for example 11 boxes of 10.

Assumptions and limits

Grout lines are neglected (they add a small extra margin).
For irregular rooms, split the floor into rectangles and add their areas before entering the total.

Frequently asked questions

How much extra tile should I buy?

Plan on 10% for straight layouts, 15% for diagonal or patterned layouts, and keep a few spares after the job — matching a dye lot years later is often impossible.

Should I include the area under a vanity?

If the vanity is freestanding or may be replaced, tile under it. Built-in cabinets can be excluded.

How many 12×24 tiles are in 100 square feet?

Each tile is 2 ft², so 50 tiles cover 100 ft². With 10% waste, order 55.