Lumber & Board Foot Calculator

A board foot (bf or fbm) is 144 cubic inches of lumber — equivalent to a board 1 inch thick × 12 inches wide × 12 inches long. It's the standard unit for buying and pricing rough and finished lumber in the US and Canada.

Formula: board feet = (thickness in × width in × length ft) ÷ 12. A standard 2×4×8 contains (2 × 4 × 8) ÷ 12 = 5.33 board feet. A 2×6×10 contains (2 × 6 × 10) ÷ 12 = 10 board feet.

Note: nominal sizes (2×4) are not the same as actual finished dimensions (1.5 × 3.5 in). Board feet are calculated from the nominal (rough-cut) size, which is what lumber yards quote and charge.

Real construction always wastes wood — saw kerfs, miscut pieces, defects, and over-ordering for safety stock. Standard waste factors: 5% for simple framing with stock lengths, 10% for general framing, 15% for hardwood furniture (matching grain), 20%+ for complex angles or compound miters.

For a deck or fence project where you can use cut-offs as blocking, 5–10% is usually plenty. For a kitchen or built-in cabinetry where every piece needs to look right, plan on 15–20%.

If you're paying delivery, round up to the next full bundle — bundle pricing is often 10–15% cheaper per board foot than picking individual pieces.

Softwood (SPF, Douglas fir, hem-fir, southern yellow pine) is what almost every framing project uses. It's sold by the piece at home centers and by the bundle or unit at lumber yards, with per-board-foot prices that swing with futures markets. As of recent quarters, dimensional softwood has ranged from $0.40/bf for stud-grade SPF up to $1.20/bf for premium kiln-dried Douglas fir.

Hardwood (oak, maple, walnut, cherry, ash) is sold rough-sawn by the board foot, almost always per MBF (thousand board feet) at the wholesale level. Hardwood prices vary far more by species and grade: red oak in FAS grade might run $4–6/bf, while walnut in the same grade can be $12–18/bf. Always confirm whether the quote is surfaced (S2S, S4S) or rough — surfacing reduces yield and changes the effective price per usable board foot.

If you're mixing species in one project, calculate board feet for each species separately and price each line individually. Averaging only works when the species and grade are identical.

Confusing nominal and actual: a 2×4 is sold as a 2×4 even though its dressed dimensions are 1.5×3.5 inches. Board feet always use the nominal size. The same applies to 1× boards (actual 0.75 in) and 5/4 decking (actual 1 in).

Mixing units: thickness and width must both be in inches, length in feet. Mixing inches and feet anywhere in the formula is the most common arithmetic error in lumber estimating.

Forgetting waste before pricing: it's tempting to multiply raw board feet by the per-bf price, but you'll come up short at checkout. Apply the waste factor first, then multiply by price — that's what the calculator above does automatically.

Ignoring length premiums: a 16-ft 2×6 often costs more per board foot than an 8-ft 2×6, because mills get fewer long clear pieces from each tree. If your design can use two 8-ft pieces with a splice, you'll usually save money.