Board foot chart for common lumber sizes

How the chart works

A board foot is a unit of volume: 144 cubic inches, or a piece 1 in thick, 12 in wide and 1 ft long. For any board, multiply thickness in inches by width in inches by length in feet and divide by 12. Every figure below comes from that one formula, rounded to two decimals.

board feet = thickness (in) × width (in) × length (ft) ÷ 12

The catch for beginners is which thickness and width to use. Softwood construction lumber is named by its nominal size — roughly the size it was sawn at while green — but it is sold dried and planed smaller. Under the American Softwood Lumber Standard (NIST PS 20) a 2×4 is dressed to 1½ × 3½ in, yet board feet are still counted on the nominal 2 × 4. That is the number a lumber yard multiplies by its price, so it is the number in the chart. If you want the measured sizes, see what is the actual size of a 2x4, what is the actual size of a 2x6 and what is the actual size of a 4x4, or look up any size in the lumber dimensions calculator.

Board foot chart: softwood lumber, 8 to 20 ft

Three sizes people often ask about, straight from the chart:

• A 1×6×8 is 4 board feet — half a board foot for every foot of length. 1×6 boards go into fence pickets, shiplap, trim and shelving. The real board is only ¾ in thick, so the wood you get is three-quarters of the billed figure.
• A 2×6×10 is 10 board feet. A 2×6 carries exactly one board foot per linear foot, so the length is the answer. Ten-footers are common for short deck joists, shed rafters and studs for 9 ft walls.
• A 2×12×16 is 32 board feet — two per linear foot. That is why wide, long joists and stair stringers are among the heaviest line items in a framing package; one 16 ft 2×12 is often enough for a stair stringer on a typical floor-to-floor rise.

For the sizes with a full worked page — the price math, the common mistakes and nearby lengths — see how many board feet in a 2x4x8, how many board feet in a 2x6x8 and how many board feet in a 4x4x8.

Shortcuts worth remembering

• 1×12 and 2×6: one board foot per linear foot, so a 16 ft piece is 16 board feet.
• 1×6 and 2×3: half a board foot per foot.
• 2×4 and 1×8: two-thirds of a board foot per foot, which is why a 2×4×12 comes out at exactly 8.
• 2×8 and 4×4: one and a third per foot. 2×12: two per foot. 6×6: three per foot.
• Doubling any dimension doubles the board feet. A 2×12 is twice a 2×6 and four times a 1×6.

Hardwood chart: board feet per linear foot

Hardwood is not sold in nominal sizes. It is sold by the quarter: its rough-sawn thickness in quarter inches. 4/4 (“four quarter”) is 1 in, 5/4 is 1¼ in, 6/4 is 1½ in and 8/4 is 2 in. Boards come in random widths and lengths, so dealers measure each one. The American Hardwood Export Council’s illustrated grading guide describes the usual method under the NHLA rules: work out each board’s surface measure (width in inches × length in whole feet ÷ 12, rounded to a whole number) and multiply by the quarter thickness. Stock thinner than 1 in is counted as 1 in. Board feet stay on the rough thickness even when the dealer planes the boards for you, so a surfaced 4/4 board around 13/16 in thick is still billed as 1 in.

To use it, pick the row for the thickness, the column nearest the board’s width, and multiply by the length. A 4/4 board 8 in wide is 0.67 board feet per foot, so at 8 ft it is 5.33 — worked through in board feet in a 4/4 hardwood board, 8 in × 8 ft. Wider than the chart? Keep going: a 24 in wide 8/4 slab is 4 board feet per foot, or 32 at 8 ft, as shown in board feet in an 8/4 slab, 24 in × 8 ft.

Going the other way: board feet to linear feet

Hardwood dealers often sell in lots of 50 or 100 board feet, and a cut list is easier to plan in running length. Divide by the board feet per linear foot from the hardwood chart: 100 board feet of 4/4 at 6 in wide (0.5 per foot) is 200 linear feet. 100 board feet of 4/4 × 6 in in linear feet shows how that turns into boards, and the board feet to linear feet calculator handles any size.

Mistakes the chart helps you avoid

• Using measured size for a softwood price. A 2×4×8 measured at 1½ × 3½ in gives 3.5 board feet; the yard bills 5.33.
• Using finished thickness for hardwood. A ¾ in part still comes out of 4/4 stock, so count it at 1 in.
• Forgetting waste. Rough hardwood loses thickness to planing and length to checked ends; add 20–30% when you buy for a project.
• Expecting the receipt to match to the decimal. Yards round each hardwood board’s surface measure to a whole number and drop fractions of a foot of length, so totals can differ from your math by a few percent — the hardwood tally calculator shows the yard’s count for a list of boards.