Board feet in a 2×8×16
There are two honest answers. The wood you actually carry out of the store is 14.50 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 21.33 BF, because board feet are by convention figured on the nominal 2″ × 8″ name.
The math, both ways
trade (nominal): 2″ × 8″ × 192″ ÷ 144 = 21.33 BF
Which one do you want? If you're figuring weight, volume, or "how much wood is that really," use 14.50. If you're comparing against hardwood priced per board foot, or reading a mill tally, use 21.33 — 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.
Sixteen feet is the longest length most yards rack. Boards this long show their flaws: sight down each one for crown (a gentle lengthwise arch) and put the crown up in any joist or rafter so load straightens it. Hauling 16-footers means a rack, a trailer, or the yard's delivery truck.
Heft check: at its true 1.5″ × 7.25″ section, a 16′ board holds 1.21 ft³ of wood — about 42 lb kiln-dried, and closer to 66 lb dripping fresh off the pressure-treated rack.
What that volume costs at hardwood prices
| Price per BF | Actual wood (14.50 BF) | Trade tally (21.33 BF) |
|---|---|---|
| $3.00 | $43.50 | $64.00 |
| $5.00 | $72.50 | $106.67 |
| $7.00 | $101.50 | $149.33 |
| $10.00 | $145.00 | $213.33 |