Tile Calculator — Tiles, Boxes & Grout
Work out how many tiles and boxes to buy for a floor, shower wall or backsplash. Includes the grout joint, a waste allowance for cuts, and an estimate of how much grout you need.
Tiles needed
How to calculate tile
- Measure the length and width of the floor or wall in feet. For L-shaped rooms, calculate each rectangle and add them.
- Enter the tile size and the grout joint width (1/8 inch is common for rectified tile, 3/16 to 1/4 inch for others).
- Choose a waste allowance and enter the coverage printed on the box to see tiles, boxes and grout.
Buying the right amount of tile
Always buy extra. Cuts at walls, corners and around fixtures cannot always be reused, a few tiles break, and you want spares for future repairs. 10% is standard for straight layouts, 15% for diagonal patterns and small rooms with many cuts, and 20% or more for herringbone. Tile batches (dye lots) vary in color, so buy everything at once and keep a few spare tiles.
The grout joint slightly reduces the number of tiles needed, which the calculator accounts for by adding the joint width to each tile's footprint. Larger tiles mean fewer joints and less grout; small mosaics use a lot.
The grout estimate is the volume of the joints (joint width × tile thickness × total joint length) converted to pounds for sanded grout. Treat it as a guide and check the coverage chart on the grout bag for your specific tile and joint size.
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Frequently asked questions
How many tiles do I need for 100 square feet?
With 12 × 12 inch tiles and a 1/8 inch joint, about 98 tiles before waste, or about 108 with 10% extra.
How much extra tile should I buy?
10% for most straight layouts, 15% for diagonal or small rooms, and 20% for herringbone or complex patterns.
Does grout width change the tile count?
Slightly. Each joint adds to the area each tile covers, so wider joints need a few fewer tiles.
Should I buy sanded or unsanded grout?
Unsanded for joints up to 1/8 inch, sanded for wider joints. Follow the tile manufacturer's recommendation.