Board feet in a 4×6×12

There are two honest answers. The wood you actually carry out of the store is 19.25 board feet — a 4×6 really measures 3.5″ × 5.5″. But if you're pricing or trading lumber, the industry counts this board as 24.00 BF, because board feet are by convention figured on the nominal 4″ × 6″ name.

The math, both ways

Which one do you want? If you're figuring weight, volume, or "how much wood is that really," use 19.25. If you're comparing against hardwood priced per board foot, or reading a mill tally, use 24.00 — 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 4×6 is for

The 4×6 is beam stock: window and door headers in western framing, deck beams, swing-set crossbars, timber steps, and the outdoor project that wants to look substantial. East of the Rockies builders usually nail up headers from doubled 2×6s; the West, with its big-timber mills, kept the solid-sawn tradition.

The comparison worth knowing: a built-up double 2×6 is 3″ thick while a solid 4×6 is 3-1/2″ — the solid beam fills a 2×4 wall's width perfectly with no plywood spacer. Like all timbers it's usually sold green or barely dried, so expect checking as it seasons, and expect real weight on the tailgate.

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 3.5″ × 5.5″ section, a 12′ board holds 1.60 ft³ of wood — about 56 lb kiln-dried, and closer to 88 lb dripping fresh off the pressure-treated rack — a genuine two-person lift.

What that volume costs at hardwood prices

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Related: 4×6×8 · all sizes