Lumber is sold by the board foot, not by the piece — and guessing wrong means a second trip to the yard or money wasted. Enter your board dimensions below to get exact board feet, linear feet and an estimated cost before you buy.
Your boards
How the math works
One board foot is a piece of wood 12″ × 12″ × 1″ — 144 cubic inches. The formula is:
Board feet = (thickness ″ × width ″ × length ft) ÷ 12
So a 1×6 board that is 8 feet long holds (1 × 6 × 8) ÷ 12 = 4 board feet. Remember that lumber sizes are nominal: a “2×4” actually measures 1.5″ × 3.5″ — always enter the actual thickness and width when it matters, or the nominal size if that is how your yard bills it (ask them — yards differ).
Tips before you buy
- Ask how the yard bills. Some yards bill on nominal size, some on actual surfaced size. On a big order the difference is real money.
- Buy 10–15% extra. Boards hide knots and warp. The waste selector above does this math for you.
- Compare species by board foot price. Our beginner’s wood guide shows which species give the most value for first projects.
- Check the fence math too. Building outdoors? The wood fence calculator counts pickets, posts and rails for you.
Frequently asked questions
How many board feet are in a 2×4×8?
Using nominal sizes: (2 × 4 × 8) ÷ 12 = 5.33 board feet. Using actual dimensions (1.5″ × 3.5″): 3.5 board feet. Framing lumber is usually priced per piece, but hardwood yards use the nominal figure.
What is the difference between board feet and linear feet?
Linear feet measure length only — a 8 ft board is 8 linear feet no matter how wide it is. Board feet measure volume, so width and thickness count. Moulding and trim are sold by the linear foot; rough hardwood by the board foot.
How do I calculate board feet for a log?
Log board footage uses log rules (Doyle, Scribner, International) based on the small-end diameter and length, and always yields less than the cylinder volume because slabs and kerf are lost. This calculator is for sawn boards.
Why did the yard charge me for more board feet than I calculated?
Most yards round up each board, bill nominal thickness on rough stock (a rough 4/4 board may bill as 1″ even after surfacing to ¾″), or add a surfacing fee. Ask for their billing method before a large order.