Enter your room size and the tile size, and get how many tiles and boxes to buy — including extra for cuts and breakage.
Start with the area you want to tile. Multiply the length by the width in feet to get the square footage. Then divide by how much a single tile covers: a 12 by 12 inch tile covers 1 square foot, a 12 by 24 inch tile covers 2 square feet, and an 18 by 18 inch tile covers about 2.25 square feet. This calculator adds 10% waste and rounds up to whole tiles.
Tile is usually sold by the box, and each box covers a set number of square feet — but that number changes with the tile size and brand. Check the box label for its coverage in square feet and enter it above, and you'll get the number of boxes to buy. When you can, buy from the same production batch so the color and shade match.
Order 10 to 15 percent extra for straight layouts to cover cuts around edges and fixtures plus the odd cracked tile. For diagonal or herringbone patterns, bump that closer to 20 percent — angled cuts waste more. Keeping a few spare tiles after the job is smart too, in case one chips later.
This is a planning aid. Tile coverage and box counts vary by product — always confirm the coverage on the actual box and round up. Buy a little extra and keep spares for repairs.