How Many Board Feet in a 2x8?

The 2x8 is where the width-loss surprise lands hardest, and I've taken the phone call more than once: "Nathan, these joists came in narrow." They didn't. A 2x8 is supposed to be 7¼″ wide, not 7½″ and that missing quarter-inch is built into the standard. The board feet, though, still ride on the nominal label — 1.333 per foot — and if that split between what you measure and what you pay for feels odd, the board foot calculation guide shows exactly where it comes from.

How many board feet are in a 2x8 by length?

At 1.333 BF per foot, a 2x8 carries a third more wood than a 2x6 of the same length. Here are the stocked lengths on both bases — the line the yard invoices and the line for the wood that shows up on your truck:

Left column: 1.333 BF × length. Right column: 0.90625 BF × length. Divide one by the other and the rate is constant at 1.47 — a 2x8 is billed at about 47% more volume than it delivers, no matter how long the stick is. Two ways I use that number: an invoice for 1,000 board feet of 2x8 is roughly 680 board feet of wood once the planer's share is removed, and every cubic foot that arrives is billed as about 17.7 board feet, not 12. If a 2x8 floor total ever looks inflated to you, that ratio is usually why, not a misread tape.

Why is a 2x8 only 7¼ inches wide?

Here's the detail that separates the 2x8 from the narrower sizes: any nominal board wider than 6 inches loses ¾″ in surfacing, not the ½″ a 2x4 or 2x6 gives up. So a 2x8 finishes at 7.25″ not 7.5″. That extra quarter-inch matters when you're fitting a ledger or matching old joists, but it does not change the board foot math — you still calculate on the nominal 2×8 because that's how softwood is priced. The full pattern, including why the cutoff sits at 6 inches, is in nominal vs actual dimensions.

How is a 2x8 floor package priced — per piece or by volume?

Home centers sell framing 2x8s by the stick; an independent yard will sometimes quote a whole floor package — joists, rim and headers together — in board feet or by the thousand board feet (MBF). Before you compare the two, get them onto one basis: a bundle of ten 2x8x12s is 120 linear feet and 160 nominal board feet, so a $600/BF line on a sheet is 16 × 6 = $96 a bundle, while the rack price per stick is the same wood counted a different way. And a 2x8x8 board feet price on any yard sheet is the nominal figure: you are paying for 10.67 BF and carrying 7.25 BF of surfaced wood. If the package mixes 2x8 joists with deeper beams or narrower blocking, I convert everything to linear feet first, then to board feet, and sanity-check the total in the guide to buying lumber by board foot.

How many board feet are in a 2x8 floor?

Floor joists are the 2x8's home turf, so picture a 12 ft × 12 ft room framed 16″ on center:

• Joists span the 12-ft width → about 10 joists, each 12 ft long = 120 linear feet.
• Two rim joists at 12 ft each = 24 linear feet.
• 144 linear feet × 1.333 BF/ft = ~192 board feet billed, or about 130 board feet (144 × 0.90625) of actual surfaced wood.

At a joist-grade rate around $0.70 per board foot (a planning estimate — #2 SYP and SPF move weekly) that frame is roughly $134 in 2x8. A double 2x8 header over a 6-ft opening, by contrast, is just 12 linear feet — 16 board feet billed, about 10.9 board feet of actual wood. I keep both kinds of takeoff — repetitive joists and one-off headers — in the cut list calculator so the rim, blocking, and headers don't get forgotten.

What are 2x8s used for?

The 2x8 is the first true load-carrying joist size most builders reach for: floor joists, deck joists, stair stringers, and shallow built-up headers. The added depth over a 2x6 buys span, which is why second-floor and deck framing leans on it. Because a single 12-ft piece is already 16 board feet, a full floor moves the material budget noticeably — worth pricing in the lumber cost calculator before you commit to a joist size.

What should you check on #2 2x8 joists at the yard?

Sight down each joist for crown and twist before it goes on the truck. A 2x8 with more than about 1/4″ of sideways bow in 12 ft will fight you on a flat ceiling. Count the grade stamps — mixed #2/#3 packs are common — and reject pieces with large edge knots near mid-span if the joist will carry living space. Board feet still use nominal 2×8; quality is a separate filter.