Board feet in a 1×4×12
There are two honest answers. The wood you actually carry out of the store is 2.63 board feet — a 1×4 really measures 0.75″ × 3.5″. But if you're pricing or trading lumber, the industry counts this board as 4.00 BF, because board feet are by convention figured on the nominal 1″ × 4″ name.
The math, both ways
trade (nominal): 1″ × 4″ × 144″ ÷ 144 = 4.00 BF
Which one do you want? If you're figuring weight, volume, or "how much wood is that really," use 2.63. If you're comparing against hardwood priced per board foot, or reading a mill tally, use 4.00 — 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 1×4 is for
The 1×4 is finish carpentry's default: door and window casing, baseboard in modest rooms, fence pickets, lattice frames, and the strapping (furring) that levels old walls and ceilings. Because it's usually visible, 1×4 is sold in more grades than structural sizes — from knotty fence boards to clear primed stock at several times the price.
A quirk worth knowing: "five-quarter" (5/4×4) deck boards live one shelf over. They look like a thick 1×4 but measure a full 1″ thick — decking's answer to the same nominal-size shrinkage story told below.
Twelve feet divides evenly into 16″ and 24″ on-center layouts, which makes it the blocking-and-plate length framers reach for. It still fits in most garages and on most roof racks — the last length that's easy to haul without flags and straps.
Heft check: at its true 0.75″ × 3.5″ section, a 12′ board holds 0.22 ft³ of wood — about 7.7 lb kiln-dried, and closer to 12 lb dripping fresh off the pressure-treated rack.
What that volume costs at hardwood prices
| Price per BF | Actual wood (2.63 BF) | Trade tally (4.00 BF) |
|---|---|---|
| $3.00 | $7.88 | $12.00 |
| $5.00 | $13.13 | $20.00 |
| $7.00 | $18.38 | $28.00 |
| $10.00 | $26.25 | $40.00 |