Dimension basis
Nominal vs actual lumber size
A board-foot calculation uses the numbers entered. Mark whether those numbers are nominal labels, measured dimensions or supplier-listed dimensions so the tally remains understandable.
Why the same board can have two size descriptions
A nominal name can describe a trade size, while the finished board may be smaller after surfacing or drying. Supplier listings can follow their own stated basis. LumberCalc never guesses a conversion because species, market and processing can change the relationship.
Which dimensions should you enter?
For a purchase estimate, use the dimension basis used by the supplier quote and label it Supplier. For measured stock, choose Actual. Choose Nominal only when you intentionally want volume from the nominal numbers and keep that assumption visible.
Frontend-only calculator