Work out how many tiles and boxes you need, including waste allowance and grout.
Tiles required equals the room area divided by the area of one tile, rounded up. A waste factor covers cuts and breakage — 10% for a straight lay, 15% for a 45° diagonal, up to 20% for complex patterns. Boxes are rounded up to the nearest whole box. Grout consumption is estimated with the formula (W + H)/(W × H) × joint_width × tile_depth × 1.44, which derives from the volume of the grout joints and a density factor for Portland-cement-based grout.
Tiles required
Tiles = ceiling(room_area ÷ tile_area × (1 + waste%))
Grout (lb/sq ft)
Grout lb/sq ft = (tile_length + tile_width) / (tile_length × tile_width) × joint × depth × 1.44
Tiles need to be cut at walls, corners and obstacles. Some tiles crack during installation. 10% waste is a safe minimum for simple straight-lay floors. Increase to 15–20% for diagonal or complex patterns where cuts waste more material.
Check the tile carton label — it lists how many tiles and the coverage area. Enter that number in the 'Tiles per Box' field.
The formula gives a good approximation for standard Portland-cement grout. Epoxy grouts and specialty mixes have different densities. Check the manufacturer's yield chart for precision.
Yes — measure the wall area (height × width) as you would a floor, and the calculation is identical.