Square Metres to Lineal Metres
Most surface materials are sold by length but laid by area. Decking, flooring boards, cladding, weatherboards, battens and lining boards are priced per lineal metre, while the job is measured in square metres. This calculator converts one to the other from the cover width of the material, adds a wastage allowance, works out how many stock lengths to order and, if you enter your supplier’s rate, what it will cost.
The formula
Lineal metres = area (m²) ÷ cover width (m). Going the other way, area = lineal metres × cover width (m). Convert the width from millimetres to metres first: 133 mm is 0.133 m.
Lineal metres per square metre by cover width
| Cover width | Lineal metres per m² | For 10 m² | For 10 m² + 10% |
|---|---|---|---|
| 65 mm | 15.38 | 153.8 | 170 |
| 90 mm | 11.11 | 111.1 | 123 |
| 133 mm | 7.52 | 75.2 | 83 |
| 140 mm | 7.14 | 71.4 | 79 |
| 180 mm | 5.56 | 55.6 | 62 |
| 230 mm | 4.35 | 43.5 | 48 |
The figures are geometry only. Your own result depends on the cover width of the product you are buying, so check the supplier’s specification rather than going by the nominal board size.
Getting the cover width right
- Decking: the board width plus the gap you will leave between boards.
- Tongue and groove flooring and lining boards: the face width without the tongue.
- Weatherboards and cladding: the exposed face after the overlap. Profiled products usually state a cover width on the product sheet.
Using the nominal size where the cover is narrower gives you too few lineal metres, and the order comes up short.
Frequently Asked Questions
What is a lineal metre? A lineal metre is one metre measured along the length of a material, whatever its width or thickness. Decking, timber, skirting, cladding and steel are commonly priced and sold by the lineal metre.
Is it lineal metre or linear metre? They mean the same thing: one metre of length. Lineal metre is the spelling most Australian timber and building suppliers use on price lists, and you will see it shortened to lm or l/m.
How do I convert square metres to lineal metres? Divide the area in square metres by the cover width in metres. For 20 m² at a 133 mm cover width, 20 ÷ 0.133 = 150.4 lineal metres, before any wastage.
How many lineal metres are in a square metre? It depends on the width of the material: 1 ÷ the cover width in metres. At 90 mm that is 11.1 lineal metres per square metre; at 140 mm it is 7.1.
What is cover width? Cover width is how much of the surface one board actually covers once it is laid. For decking it is the board width plus the gap. For tongue and groove flooring, weatherboards and cladding it is the face left showing after the tongue or overlap, which is less than the nominal size. Use the supplier’s stated cover width where there is one.
How do I work out how many lengths to buy? Divide the lineal metres including wastage by the stock length and round up. 165.4 lineal metres in 5.4 m lengths is 30.6, so 31 lengths. Pick a stock length that suits your runs, as offcuts from a length that does not divide into the run are often too short to reuse.
How much wastage should I allow? The calculator starts at 10%. Allow more where there are a lot of cuts, angles or short runs, and less for long straight runs where the stock length divides evenly into them.
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