Calculate the number of tiles or flooring planks needed for any room. Includes wastage percentage, grout joint spacing, pattern offsets, and total material cost estimate.
X is what % of Y: (X ÷ Y) × 100
X% of Y: (X ÷ 100) × Y
% change from A to B: ((B − A) ÷ A) × 100
Original value before X% added: Final ÷ (1 + X/100)
Original value before X% removed: Final ÷ (1 − X/100)
Worked examples: 45 is what % of 180? (45 ÷ 180) × 100 = 25%. 15% of 240? 0.15 × 240 = 36. Price rose from 80 to 96 — % increase: ((96−80) ÷ 80) × 100 = 20%. Price was 120 after 20% tax added — original pre-tax: 120 ÷ 1.20 = 100.
Calculate the room area (length × width), divide by the area of one tile (including grout joint), then add a wastage allowance of 10% for standard rooms and 15% for diagonal or pattern cuts.
Allow 10% extra for straight-lay patterns, 15% for diagonal (45°) laying, and up to 20% for complex patterns or rooms with many cuts around obstacles.
A grout joint is the gap left between tiles, typically 2–10mm wide, filled with grout after tiling. Larger tiles usually use wider joints (3–5mm); mosaic tiles may use 1–2mm.
This varies by tile size and manufacturer, but your tile supplier will state how many m² each box covers. Divide your total area (including wastage) by the m² per box to find the number of boxes.
Yes, if the existing tiles are firmly adhered, flat, and the added height won't cause problems with doors or transitions. The substrate must be sound and the adhesive must be compatible.