Last updated:
A 12 by 12 inch tile covers exactly one square foot, which makes it the easiest size to estimate: the raw tile count is simply the area in square feet. A 10 by 12 foot room of 120 square feet needs 120 tiles before waste and 132 with a 10 percent allowance. This page opens in feet and inches with the size already set. The same calculation works for mosaic sheets, since most small mosaics, from penny rounds to one inch squares, are sold mounted on mesh sheets of roughly 12 by 12 inches. Enter the sheet size rather than the individual pieces and the result is the number of sheets. Check the actual sheet dimensions on the box, as some are 11.8 or 12.5 inches, which changes the count on a large area. Twelve inch tiles are forgiving: they follow a slightly uneven floor better than large formats, waste less on cuts, and suit small bathrooms where big tiles leave awkward slivers. The trade off is more grout lines to lay and clean. Allow 10 percent waste for a straight lay and 15 percent for diagonal. The metric near-equivalent is 30x30 Tile Calculator: Tiles per m², Boxes & Waste (cm), and for larger formats see 12x24 Tile Calculator: How Many Tiles & Boxes per Sq Ft.