Board feet in a 2×8×8
There are two honest answers. The wood you actually carry out of the store is 7.25 board feet — a 2×8 really measures 1.5″ × 7.25″. But if you're pricing or trading lumber, the industry counts this board as 10.67 BF, because board feet are by convention figured on the nominal 2″ × 8″ name.
The math, both ways
trade (nominal): 2″ × 8″ × 96″ ÷ 144 = 10.67 BF
Which one do you want? If you're figuring weight, volume, or "how much wood is that really," use 7.25. If you're comparing against hardwood priced per board foot, or reading a mill tally, use 10.67 — 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 2×8 is for
The 2×8 is the workhorse joist for decks, porches, and additions — good for roughly 12′ of span at 16″ on center in southern pine, a bit less in SPF. Doubled up, it's a common header over doors and windows in non-load-bearing situations.
It's also the sweet spot for the rip-your-own trick: a straight-grained 2×8 ripped down the middle yields two clear-ish 2×4-ish boards with far fewer knots than actual 2×4 stock, because wider framing lumber is cut from bigger, older trees.
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″ × 7.25″ section, a 8′ board holds 0.60 ft³ of wood — about 21 lb kiln-dried, and closer to 33 lb dripping fresh off the pressure-treated rack.
What that volume costs at hardwood prices
| Price per BF | Actual wood (7.25 BF) | Trade tally (10.67 BF) |
|---|---|---|
| $3.00 | $21.75 | $32.00 |
| $5.00 | $36.25 | $53.33 |
| $7.00 | $50.75 | $74.67 |
| $10.00 | $72.50 | $106.67 |