Area = length × width (in feet). One tile covers tile length × tile width ÷ 144 square feet. Tiles needed = area ÷ tile area, rounded up. Waste covers cuts, breakage and mistakes: 10% is typical for straight layouts, 15% for diagonal or herringbone patterns and 15 to 20% for small rooms with many cuts. Boxes = tiles to buy ÷ tiles per box, rounded up. Tiles from different production batches can differ slightly in color, so buy everything at once and keep a few spares.
Example: a 12 × 10 ft floor is 120 sq ft. Each 12 × 12 in tile covers 1 sq ft, so you need 120 tiles, or 132 with 10% waste. At 10 tiles per box that is 14 boxes.
Ten percent for simple layouts, 15% for diagonal patterns or rooms with lots of corners, and more for very small tiles or natural stone that needs sorting.
No. Grout joints are narrow and the difference is small for a whole room. For large-format tiles with wide joints, enter tile sizes that include the joint (for example 12.25 in instead of 12).
Split it into rectangles, calculate each one and add the results, or use the square footage calculator to get the total area first.
See also: square footage calculator · paint calculator · concrete calculator