Hardwood mills sell their product by volume, not by length. The unit of measure is the “Board Foot”, which represents a surface area of one square foot, one inch thick.
To convert linear feet to board feet, use this formula:
Thickness (in inches) x Width (in inches) x Length (in inches)
Hardwood is normally measured in the rough before kiln drying and that measurement stays with it for life. Trimming and planning adds some waste and all lumber shrinks in kiln drying. The universally established practice is for the wholesaler to sell the lumber on the basis of adding an average allowance for the kiln drying to his own tally. The additional is usually 7%. When hardwood is sold at the retail level, this allowance is usually already included in the tally.
Sound confusing? It gets easier with practice. Why not drop into Windsor and try out your new found measuring skills. Windsor stocks a good supply of fine hardwoods.
One board at 1” x 6” x 120″ = 5 board feet
eg: 1” x 6” x 120″
––––––––––––––––– = 5 BF