1 Board Foot =
1 ft × 1 ft × 1 in =
12 in × 12 in × 1 in =
30.48 cm x 30.48 cm x 2.54 cm.
One thousand board feet should therefore be around 2.36 m³ of lumber, correct? In most cases, unfortunately not, though.
In North America, most of the softwood lumber is sold to timber construction companies as so-called dimensional lumber, which used to be fresh, unplaned wood, usually with a cross-section of 2 by 4 inches. At some point, though, dry, planed wood became the new dimensional lumber. In practice, this meant subtracting a quarter inch of planing allowance on each side. Nominally, the product is still called 2-by-4 (nominal size), but in reality (i.e. actual size), it measures only 1.5 x 3.5 inches. Thus, it is 34% smaller than what its name suggests. As a result, one thousand board feet of this dimensional lumber correspond to only 1.55 m³.
Real-life example
Conversion of US units of measurement into the metric system: 1,000 bft of 2-by-4 correspond to 2.36 m³ in nominal size and 1.55 m³ in actual size. Despite being called 2-by-4, the product’s actual size is 3.5 by 1.5 inches © Timber-Online.net
Lately, 2-by-4 cost US-$500/1,000 bft – or €454/1,000 bft with the current exchange rate of US-$1.1/€.
Nominally, 1,000 bft are 2.359737 m³. So, the next calculation is: 454 divided by 2.36. Converted into nominal cubic meters, this equals €192.6/m³.
On the US market, however, billing is done based on “actual size”. Therefore, you have to take the difference between actual size and nominal size into account. The conversion factor is 2 times 4 divided by 1.5 times 3.5 – i.e. 1.5238.
The last step involves multiplying €192.6/m³ times the factor 1.5238 which equals around €293.5/m³.
