Plank Calculator — Calculate Planks Needed

Measure the room length and width in millimetres. Enter your plank dimensions (width and length). The calculator divides the room width by the plank width to get rows, and the room length by plank length to get planks per row. Always add 10% for waste from cuts and offcuts.

For outdoor decking, a 5–8mm gap is recommended for drainage and expansion. For interior flooring, tongue-and-groove planks typically have no visible gap. For cladding, the gap depends on the profile style.

Allow 10% for standard rectangular rooms. For L-shaped rooms, rooms with many obstacles, or diagonal layouts, increase to 15%. For herringbone or chevron patterns, allow 15–20% waste.

Common UK plank widths are: flooring boards 90–140mm, decking boards 120–150mm, cladding boards 100–150mm, and wide-plank flooring 180–220mm. Length varies from 1800mm to 4800mm depending on the product.