Timber Calculator Australia — Lineal Metres from Area
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Lineal metres
Board count by standard length
All standard lengths — boards needed
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How to calculate lineal metres of timber for any area in Australia
To find how many lineal metres of board are needed to cover an area, divide the area by the board width in metres (not including the gap). Then multiply by (board width + gap) / board width to account for spacing — or simply: LM = area ÷ (board width in m). Add your wastage percentage for cuts. To convert LM to board count, divide total LM by your chosen board length and round up. Australian standard timber lengths are 1.8 m, 2.4 m, 3.0 m, 3.6 m, 4.2 m, 4.8 m and 6.0 m. Availability varies by species and supplier.
Timber calculator — FAQs
What is the difference between lineal metres and square metres for timber?
Lineal metres (LM) measures total length regardless of width — it's how Australian timber merchants sell boards. Square metres (m²) measures area. To convert m² to LM, divide the area by the board width in metres (e.g. a 90 mm wide board: 20 m² ÷ 0.090 m = 222 LM). To convert LM to m², multiply by the board width. This calculator handles the conversion automatically including gap and wastage.
What gap should I leave between decking boards in Australia?
A 5–6 mm gap is standard for hardwood decking (spotted gum, blackbutt, merbau) installed in seasoned condition — it allows for minor movement and drainage. For softwood decking (pine, treated pine) installed unseasoned, use a 3–4 mm gap as the timber will shrink as it dries. Gaps less than 3 mm trap debris and moisture; gaps over 8 mm become a trip hazard and may not meet NCC requirements. A 5 mm spacer (cut from a piece of hardboard or offcut) is the easiest way to maintain consistent spacing.
What are standard decking board widths in Australia?
Common Australian decking board widths: 70 mm (narrow, for small decks or feature strips), 90 mm (the most common standard residential width), 140 mm (wide boards, less common, can show more cupping). Face widths are the dressed dimension — the actual coverage width after seasoning. A 90 mm board at 5 mm gap covers 95 mm per board run; this calculator accounts for that automatically.
How much extra timber should I order for wastage?
10% is standard for a simple rectangular deck or fence with straight cuts. Increase to 15% for L-shaped or irregular areas, and 20% for 45° diagonal patterns (which require significantly more cuts). Always round up to the nearest board — you can't buy half a board at the timber yard. Having a few boards left over is far less costly than a second delivery.
What is the best decking timber in Australia?
Hardwoods dominate Australian residential decking: spotted gum and blackbutt are extremely durable (Class 1–2 above ground) and native to eastern Australia; merbau (imported) is popular for its consistent reddish-brown colour; jarrah is valued in WA. All require proper gapping and fastening. Treated pine (H3 or H4 treated) is the budget option and widely available, but requires regular oiling to prevent surface checking. Composite decking is growing in popularity for its low maintenance but costs more upfront.