Enter a board’s thickness, width and length to get its volume in board feet — the unit lumber is bought and sold in.
What Is a Board Foot Calculator?
A board foot is lumber’s volume unit: 144 cubic inches — a board 1 inch thick, 12 inches wide and 12 inches long. Lumber is priced per board foot, so the formula (thickness × width × length in feet) ÷ 12 converts any board: a 2×6 that is 12 ft long = (2 × 6 × 12) ÷ 12 = 12 board feet. Nominal vs actual sizes are the trap: a “2×6” is actually 1.5 × 5.5 inches — this tool uses the dimensions you enter, so use actual or nominal consistently and know which you priced.
How to Use the Board Foot Calculator
- Enter the board’s thickness and width in inches.
- Enter the length in feet.
- Enter how many identical boards.
- Click “Calculate Board Feet” for the total.
Board Foot Calculator Formula
Board feet = (thickness in × width in × length ft) ÷ 12 × number of boards.
Worked Example
A 2 × 6 × 12 ft board: (2 × 6 × 12) ÷ 12 = 12.00 board feet. Ten of them = 120 board feet.
How It Works, In Plain Words
A board foot is a measure of volume, not of length or area: one board foot is 144 cubic inches of wood — the volume of a board 1 inch thick, 12 inches wide and 12 inches long. The tool works in three steps. First, it multiplies your three dimensions together: thickness in inches, width in inches and length in feet. For the worked example that is 2 × 6 × 12. Second, it divides by 12, which converts that mixed-unit product into board feet — the divisor is 12 because the length is in feet while the other two dimensions are in inches, and 144 cubic inches make one board foot. Skip the division and the answer comes out far too big. Third, it multiplies by the number of boards, so a whole stack of identical boards is priced in one go: ten of the example boards give 120 board feet in total. The result shows both figures — the total board feet and the per-board figure — so you can check a quote line by line. Everything uses the dimensions you type: the tool never adjusts nominal sizes to actual ones for you.
Real-World Uses
Pricing a hardwood order. A supplier quotes per board foot, so the total from this tool is the number the price hangs on: run the board size and count, then multiply the total board feet by the quoted price per board foot, exactly as the pricing FAQ below describes. Comparing two suppliers’ quotes. One yard may price on nominal sizes and another on actual — the page’s own warning. Running both size sets through the tool shows whether a cheaper-looking quote is really cheaper, or just measured differently. Planning a deck or stair project. The Benefits list notes this tool pairs with the Deck and Stair calculators: once a design fixes the board sizes, this tool turns the parts list into a total board-foot figure for ordering and budgeting.
Benefits of a Board Foot Calculator
- The trade’s pricing unit, computed instantly
- Multiple boards in one calculation
- Nominal/actual note keeps quotes honest
- Pairs with the Deck and Stair calculators
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device.
Common Mistakes to Avoid
- Mixing nominal and actual sizes when comparing quotes — know which your supplier uses
- Entering length in inches instead of feet (the formula needs feet)
- Forgetting the ÷ 12: the raw product is 144× too big
More Common Mistakes to Avoid
The list above covers the classic traps — mixing nominal and actual sizes, entering length in inches, and forgetting the ÷ 12 — and a few more are worth a mention. The first is pricing from the per-board figure when the quote covers a stack: the tool shows both numbers, and the total is the one that already includes your board count — ten boards at 12.00 board feet each is 120, not 12. The second is entering the board count as zero or leaving it blank and wondering why the answer looks small: the tool treats a missing or under-one count as a single board. The third is trusting a dimension you have not measured: because the tool uses exactly the dimensions you enter, a guessed thickness flows straight into the total, so measure the stock — or confirm which size convention the supplier’s price assumes — before you rely on the figure.
Frequently Asked Questions
How many board feet in a 2 × 6 × 12 ft board?
12.00 board feet.
What is a board foot?
144 cubic inches of lumber — a 1 × 12 × 12 in board.
Is a 2×4 really 2 by 4 inches?
No — nominal 2×4 is actually 1.5 × 3.5 inches after surfacing. Use one convention consistently.
How do I price lumber?
Multiply total board feet by the price per board foot quoted by your supplier.
Does length go in feet or inches?
Feet in this tool’s formula — 12 ft, not 144 in.
I have ten identical boards. Do I calculate each one separately?
No. Enter the size once, set the number of boards to 10, and the tool multiplies for you: the worked example’s board is 12.00 board feet, so ten of them total 120 board feet. The per-board line stays on screen so you can check the single-board figure too.
What does the tool do if I leave the number of boards blank?
It treats the count as one board, so you still get the single-board figure. The same applies to a count under one — the tool never multiplies by zero, which would wipe out a valid board size.