Tile Calculator

What It Does

This calculator works out how many tiles and how many boxes a floor or a wall needs. Enter the area, the tile's length and width, the grout joint and the waste allowance: it widens each tile by the joint to get the area one tile really covers, divides the area by that, rounds up to whole tiles and adds the waste. It then divides the tiles by how many a box holds, rounds up again, and reports the tiles, the boxes and the area those tiles will cover.

Real-World Usage

Tiles are sold in whole boxes, and a box that has been opened can rarely be returned, so over-ordering eats into the budget while under-ordering stops the job. Use the calculator before a bathroom or kitchen floor, a splashback or a wall run to buy whole boxes and to see what the waste allowance costs on a large floor.

Local Context

A 10% allowance is the usual figure for a straight lay and 15% or more for a diagonal or herringbone pattern, where the edge cuts waste more. Joints are quoted in the tile's own unit — 2 to 3 mm is a common wall joint — and they matter: a 60 cm tile with a 3 mm joint covers 0.3636 m², not the 0.36 m² of the tile alone.

How many 12 inch tiles do I need for 100 square feet?

100 tiles cover 100 sq ft exactly, because a 12 × 12 in tile is one square foot. With the 10% waste allowance the order becomes 110 tiles — and 11 boxes if a box holds ten.

Do I need extra tiles for cuts?

Yes. A straight lay usually loses about 10% of the tiles to edge cuts, breakages and later repairs, and a diagonal lay 15% or more. Type your own percentage into the waste field.

Should I add the grout joint to the tile size?

No — enter the tile's own size and the joint separately. The calculator adds the joint to both sides of the tile, which is the area the tile really occupies once it is laid.

How do I work out how many boxes to buy?

Divide the tiles you need by the tiles in a box and round up: 110 tiles at 10 per box is 11 boxes, and at 8 per box it is 14 boxes. The boxes field does that division for you.