Board feet in a 2×6×8
There are two honest answers. The wood you actually carry out of the store is 5.50 board feet — a 2×6 really measures 1.5″ × 5.5″. But if you're pricing or trading lumber, the industry counts this board as 8.00 BF, because board feet are by convention figured on the nominal 2″ × 6″ name.
The math, both ways
trade (nominal): 2″ × 6″ × 96″ ÷ 144 = 8.00 BF
Which one do you want? If you're figuring weight, volume, or "how much wood is that really," use 5.50. If you're comparing against hardwood priced per board foot, or reading a mill tally, use 8.00 — 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 2×6 is for
The 2×6 took over exterior walls as energy codes tightened: its 5-1/2″ bay holds R-19+ insulation where a 2×4 wall maxes out around R-13. It's also the standard deck joist for short spans, the rafter for small roofs, and — laid flat — the classic deck board's beefier cousin.
Spans are where 2×6 thinking matters: as a floor joist it's only good for about 9′ at 16″ spacing in most species, which is why you'll find it in sheds and landings but 2×8s and up under real floors.
Eight feet is the default length — it matches the ceiling, fits inside a pickup bed with the tailgate down, and wastes the least when cut for typical walls. It's usually the cheapest per foot, too, because it's the volume seller.
Heft check: at its true 1.5″ × 5.5″ section, a 8′ board holds 0.46 ft³ of wood — about 16 lb kiln-dried, and closer to 25 lb dripping fresh off the pressure-treated rack.
What that volume costs at hardwood prices
| Price per BF | Actual wood (5.50 BF) | Trade tally (8.00 BF) |
|---|---|---|
| $3.00 | $16.50 | $24.00 |
| $5.00 | $27.50 | $40.00 |
| $7.00 | $38.50 | $56.00 |
| $10.00 | $55.00 | $80.00 |