Hardwood Board Foot Calculator

How are hardwood board feet measured?

Hardwood lumber is graded and priced by the actual dimensions of the board — its real thickness, width, and length. That is the opposite of softwood 2×4s, which are priced by nominal size. Two rules from the National Hardwood Lumber Association (NHLA) drive the math:

• Thickness rounds up to the nearest quarter inch. A board planed to 0.9″ is still billed as 4/4 (1″). A rough 1.1″ board is billed as 5/4 (1.25″).
• Each board's board feet rounds to a whole number. Boards are tallied individually, not summed then rounded, which is why a long cut list can differ from a single calculation.

Quarter thickness chart (4/4 to 12/4)

Full detail on each size lives in the hardwood lumber thickness guide.

How does NHLA rounding change a board's tally?

Here's the kind of board I tally every week. Say you want a 6/4 walnut board, 7⅜″ wide and 8 ft long. Enter thickness 6/4 (the calculator reads it as 1.5″), width 7 3/8, and length 8. The net board feet are 1.5 × 7.375 × 8 ÷ 12 = 7.38 BF, billed as 7 BF after NHLA rounding to the nearest whole foot. Add a walnut price to see cost, and the result shows estimated weight from walnut's density (about 3.2 lb/BF).

Now stretch that board to 9⅝″ wide and the net jumps to 1.5 × 9.625 × 8 ÷ 12 = 9.63 BF, which rounds up to 10 BF. The rounding can swing either direction by board, but across a 200-piece pack it tends to land in the seller's favor — which is why I always run my own tally before signing.