How many planks or tiles your floor needs — room area, waste allowance and material cost in one pass.
10% is standard; use 15% for diagonal lays or rooms with many corners.
How to use this tool
Length and width in metres, centimetres, feet or inches — measure the longest points, including alcoves, or measure in sections.
Plank or tile length and width in cm, mm, inches or metres, from the product listing.
Under Advanced options: 10% is standard, 15% for diagonal patterns or rooms with many corners and cuts.
The big number is pieces to buy, with area, waste pieces and material cost underneath.
Formula & worked example
Worked example: a 4 m × 3 m room is 12 m². With 120 cm × 20 cm planks (0.24 m² each), 12 ÷ 0.24 = 50 planks before waste, and 50 × 1.10 = 55 planks with a 10% allowance. At 8 per plank, the material costs 440.
Limitations — read this before you rely on it
This counts area, not layout: it does not stagger joints, match plank lengths to room dimensions, or reserve whole planks for awkward cuts — diagonal lays, herringbone and rooms with many nooks need extra. Always keep a few spare pieces for future repairs.
Frequently asked questions
10% over the net area is the standard waste allowance for straight lays; 15% for diagonal lays, herringbone or rooms with many corners. This calculator applies your allowance and rounds up to whole pieces.
Split it into rectangles, calculate each area separately, and add them. Or enter the total area as a rectangle of the same area — the piece count is the same, though the layout plan still needs the real shape.
Doorways add a little area; skirting boards do not change the floor area. Measure wall to wall, and add any doorway recesses to the room area.
For the piece count, only area matters. For the look, stagger joints by at least 30 cm, avoid slivers under 5 cm at walls, and run planks along the longest wall or towards the main light source.
Underlay is sold by area — use the room area shown here. Beading and thresholds are sold by length, so measure the room perimeter separately.