CalcStack — free, instant, no signup. The interactive calculator loads automatically.
Hardwood is sold by the board foot. Do the math before the lumberyard.
Hardwood and rough lumber are priced by the board foot — a volume unit that trips up everyone the first time: thickness in inches times width in inches times length in feet, divided by 12. This calculator runs the count for one board or a whole stack, and prices it at your supplier's per-BF rate.
Woodworkers buying hardwood and anyone pricing rough lumber at a sawmill use this: board feet is a volume unit that looks like an area unit until the invoice arrives. Run the stack count before the lumberyard, not after.
2 × 6 × 8 ÷ 12 = 8 board feet, using nominal dimensions. That is the convention at the lumberyard — a "two by six" bills as a full 2"×6" even though the dressed board measures 1.5"×5.5".
Rough hardwood thickness in quarter-inches: 4/4 = 1" rough, which planes to about ¾". You pay for the rough dimension — a finished ¾" board still bills as 1" (one BF per square foot per foot of length).