How it is calculated
The volume of one piece is thickness × width × length in metres. If you know the number of pieces, the batch volume is the volume of one piece times the count. If you know the volume, the number of pieces is the volume divided by one piece, rounded up. The cost uses the price per cubic metre, per piece or per running metre, as the shop lists it.
Formula
Piece volume, m³ = thickness (m) × width (m) × length (m)Pieces per m³ = 1 ÷ piece volumeRunning metres = quantity × lengthExample
A 50 × 150 mm board 4 m long is 0.03 m³, so a cubic metre holds 33.3 of them. 20 boards are 0.6 m³, or 80 running metres.
Tips from practice
- Green timber is heavier and shrinks 3–5 % across the width as it dries, so allow for it in cladding.
- Add 5–10 % for defects, knots and offcuts.
- Planed timber is smaller than sawn: 50 × 150 sawn is usually 45 × 145 mm planed.
Questions and answers
How many 50 × 150 × 6 m boards are in a cubic metre?
22.2 boards, as one board is 0.045 m³.
How many 150 × 150 × 6 m beams are in a cubic metre?
7.4 beams: one beam is 0.135 m³.
Why does the shop count fewer boards per cubic metre?
Sellers sometimes use nominal sizes or round the numbers. Check the real section and length with a tape.
Found a mistake in a formula? Write to [email protected]