Multiply room length by room width to get the area, then add a waste factor (typically 10%) to account for cuts and offcuts: area to purchase = room area × (1 + waste%). For example, a 5 m × 4 m room is 20 m² net; with 10% waste you need 22 m². Always round up — running short mid-installation forces a return trip and risks a batch-colour mismatch. For L-shaped rooms, split into rectangles and add the areas.

Use 10% for a straight lay (the most common pattern), 15% for a diagonal lay (planks at 45°), and 20% for herringbone or chevron patterns, which require many angled cuts. Add an extra 5% for rooms with many alcoves, doorways, or columns. The waste factor covers offcuts, breakage, and any pieces needed for future repairs. Never go below 5% even for simple rectangles — manufacturing tolerances mean you will always lose some material.

Divide the total area to purchase (including waste) by the area of one plank, then round up. For example, with 22 m² to purchase and planks that are 1.22 m × 0.20 m (0.244 m² each): 22 / 0.244 = 90.2 → 91 planks. Standard hardwood planks in many markets are 120 cm × 20 cm (about 4 ft × 8 in), covering 0.24 m² each.

Yes — diagonal (45°) patterns increase waste to 15% because every plank at the room perimeter must be cut at an angle, producing offcuts that cannot be reused.

Herringbone and chevron patterns typically require 20% extra because the short-end cuts from one row rarely fit the required angle at another. For herringbone on a large open floor with few walls, you may get away with 15% — but 20% is the safe standard. These patterns also take longer to install, so factor that into your budget.