How to Calculate How Much Tile You Need
Start by measuring the width and length or height of each surface that will receive tile. For floors, multiply the room's width by its length. For walls and backsplashes, multiply the width by the height.
If your project includes several separate surfaces, calculate each one and combine their areas. Areas that will not receive tile, such as doors, windows, cabinets, or other openings, can then be deducted.
How Much Extra Tile Should You Buy?
Buying exactly the calculated square footage usually isn't a good idea. Extra tile may be needed for cuts, breakage, damaged pieces, pattern matching, and future repairs.
A 10% waste allowance is commonly useful for a straightforward tile project, while projects with numerous cuts or more complicated layouts may require additional material.
Keep in mind that openings don't always reduce the amount of tile you need to purchase by their full area. A cut tile used around an opening may leave a leftover piece that cannot be reused elsewhere.
Tile Size, Grout Joints, and Layout
The size of the grout joint affects the spacing between tiles and therefore the number of rows, columns, and edge cuts in a tiled surface.
For the most accurate layout estimate, enter the tile's actual measured dimensions rather than relying only on its nominal advertised size. A tile sold as a particular size may have slightly different manufactured dimensions.
The calculator's layout estimates are intended for straight rectangular layouts. Diagonal, herringbone, basketweave, Versailles, and other complex patterns can require different calculations and usually produce different amounts of waste.
Tiles per Box vs. Square Feet per Box
Tile manufacturers may list either the number of tiles in a carton or the amount of area that one carton covers.
When the manufacturer provides square-foot or square-meter coverage per box, use that figure when determining how many boxes to purchase. Package coverage varies between tile products, even when the individual tiles appear to be similar in size.
Don't Forget the Other Tile Materials
Tile itself is only part of a typical installation. Depending on the project, you may also need mortar or adhesive, grout, backer board or another suitable substrate, waterproofing materials, spacers, trim or edge profiles, sealant, and other installation supplies.
Coverage for products such as mortar and grout varies by product and installation conditions, so check the manufacturer's coverage information for the specific materials you're using.