Board feet in a 2×12×10
There are two honest answers. The wood you actually carry out of the store is 14.06 board feet — a 2×12 really measures 1.5″ × 11.25″. But if you're pricing or trading lumber, the industry counts this board as 20.00 BF, because board feet are by convention figured on the nominal 2″ × 12″ name.
The math, both ways
trade (nominal): 2″ × 12″ × 120″ ÷ 144 = 20.00 BF
Which one do you want? If you're figuring weight, volume, or "how much wood is that really," use 14.06. If you're comparing against hardwood priced per board foot, or reading a mill tally, use 20.00 — the whole trade runs on nominal, for the historical reasons on our nominal vs actual page. (Construction lumber itself is usually priced per piece, so at the store neither number appears on the shelf tag.)
What a 2×12 is for
The 2×12 is the biggest common dimensional board, and it has one famous job: stair stringers. Cutting the sawtooth for treads and risers eats so much width that only a 2×12 leaves enough uncut wood (the code minimum "throat") to carry the load. It's also the long-span joist, the ridge board, and the site-built beam.
Big boards concentrate the drying stresses of the tree, so a stack of 2×12s hides more crook and wane than a stack of 2×4s. Sight down every one, and plan cuts around the heart center if a board contains it.
Ten-footers are the remodeler's length: enough extra to clear a 9′ ceiling, cut around a split end, or get two 57″ pieces with margin. Many yards price them barely above 8′ stock, making them quiet bargains per usable foot.
Heft check: at its true 1.5″ × 11.25″ section, a 10′ board holds 1.17 ft³ of wood — about 41 lb kiln-dried, and closer to 64 lb dripping fresh off the pressure-treated rack.
What that volume costs at hardwood prices
| Price per BF | Actual wood (14.06 BF) | Trade tally (20.00 BF) |
|---|---|---|
| $3.00 | $42.19 | $60.00 |
| $5.00 | $70.31 | $100.00 |
| $7.00 | $98.44 | $140.00 |
| $10.00 | $140.63 | $200.00 |