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Tile Calculator

Work out how many tiles or boxes of flooring to buy for a floor or wall, with the waste you choose.

Area lengthArea widthThe floor or wallGrout jointTile lengthTile widthClose-up
Key The area to cover, and one tile with its grout joint.
Units
Work out by
Area to cover

Add a rectangle for each part of an L-shaped or split room.

Common tile sizes. 12 in, 16 in and 24 in squares, and 12 x 24 in rectangles. Use the size printed on the box. Editorial rule of thumb.
in
in
in
%
Area100 sq ft
Tiles with no waste100
Tiles to buy, with waste110 tiles
Area the tiles cover110 sq ft

10 × 10 ft = 100 sq ft. 100 sq ft ÷ one 12 × 12 in tile = 100 tiles; with 10% waste = 110, rounded up to 110.

Diagonal or patterned layouts need more waste, commonly 15%. Grout and adhesive are not included.

Fig. 1 Tiles for your floor or wall.

Every formula is tested against worked examples. How we check

WasteTilesArea
5%105 tiles105 sq ft
10%110 tiles110 sq ft
15%115 tiles115 sq ft

Fig. 2 The same floor at common waste allowances.

Last checked 11/10/2026. Defaults are editorial rules of thumb; each one is explained in the guide below.

Guide

How the amount is worked out

Each tile covers its own size plus half a grout joint on each side. Tiles = area ÷ (tile length + joint) × (tile width + joint). Add waste, then round up to whole tiles, then to whole boxes.

Example. 100 sq ft of 12 × 12 in tiles with no grout joint is 100 tiles. Add 10% waste and you need 110 tiles.

How much waste?

10% is a common starting point for straight layouts. Diagonal or patterned layouts, rooms with many corners and small tiles need more; 15% is common for diagonal layouts. Keep a few spares from the same batch for future repairs, because dye lots vary.

Flooring by box

Plank flooring is sold by box, and each box lists its coverage in square feet. Switch to "by box coverage" and enter the figure from the box. Round up to whole boxes.

What is not included

Grout, thin-set and underlayment depend on tile size, joint width and trowel notch, and there is no single defensible coverage figure, so this calculator leaves them out. Check the bag or the manufacturer’s coverage table.

Common questions

How many tiles for 100 sq ft?

With 12 x 12 in tiles and no joint, 100 tiles; with 10% waste, 110 tiles. Smaller tiles mean more of them.

Should I measure the room twice?

Yes. Add rooms made of several rectangles one after another and double-check measurements before ordering.

Does the grout joint matter?

A little. A 1/8 in joint on 12 in tiles makes each tile cover about 2% more, which can save a tile or two.

What if I change tile later?

Buy all tiles from the same batch, as colours can differ between production runs.

Worked examples

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