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Board Foot Calculator

Construction

Calculate board feet of lumber from thickness, width, length, and quantity. Get total board feet and cost estimates for any lumber order, fast and free.

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Total Board Feet

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Board Feet per Piece
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This calculator computes your Total Board Feet, Board Feet per Piece from the values you enter.

Inputs
Thickness (in)Width (in)Length (ft)Quantity (pieces)
Outputs
Total Board FeetBoard Feet per Piece

What is a Board Foot?

A board foot calculator converts the dimensions of a piece of lumber — thickness, width, and length — into board feet, the standard volume-based unit used to price and order lumber in the United States. One board foot equals 144 cubic inches, equivalent to a board that is 12 inches wide, 12 inches long, and 1 inch thick. Unlike a linear foot, which measures only length, a board foot accounts for the full volume of wood, which is why lumber yards, mills, and hardwood suppliers use it as their standard pricing unit.

This matters because two boards of identical length can contain very different amounts of wood. A 1×6 board and a 2×12 board of the same 8-foot length are nowhere close in volume, and pricing them the same way per linear foot would be inaccurate. The board foot formula — thickness (in) × width (in) × length (ft) ÷ 12 — normalizes for all three dimensions at once, giving buyers and sellers a consistent way to compare and price lumber regardless of its cross-section.

This tool is especially useful when planning woodworking projects, framing jobs, or bulk lumber purchases where you need to convert raw dimensions into a quote-ready quantity. Pair it with the Cubic Yard Calculator if your project also involves concrete footings or the Square Footage Calculator if you're estimating flooring or sheet material coverage.

How to use this Board Foot calculator

  1. Enter the Thickness (in) of the board you're measuring, in inches — the default is 1 inch, a common surfaced hardwood thickness.
  2. Enter the Width (in) of the board, in inches — adjust the slider or type an exact value up to 24 inches.
  3. Enter the Length (ft) of the board, in feet — lumber length is conventionally measured in feet, not inches.
  4. Enter the Quantity (pieces) — the number of identical boards you need at these dimensions.
  5. Read the Total Board Feet result at the top — this is your order quantity for pricing purposes.
  6. Check Board Feet per Piece to verify the per-board math, then repeat the process for any additional board sizes in your project and add the totals together.

Formula & Methodology

The board foot formula is:

Board Feet per Piece = (Thickness × Width × Length) ÷ 12

Where thickness and width are measured in inches and length is measured in feet. The division by 12 converts the result from cubic inches into the standard board foot unit (144 cubic inches ÷ 12 = 12, matching the 1"×12"×12" reference board).

Total Board Feet = Board Feet per Piece × Quantity

Worked example: For a board that is 1 inch thick, 6 inches wide, and 8 feet long:

Board Feet per Piece = (1 × 6 × 8) ÷ 12 = 48 ÷ 12 = 4 board feet

If you need 10 of these boards: Total Board Feet = 4 × 10 = 40 board feet. At a hypothetical price of $6.50 per board foot for a hardwood species, that order would cost approximately $260 before tax — always confirm current per-board-foot pricing with your supplier.

Frequently Asked Questions

A board foot is the standard unit of volume used to measure and price lumber in the United States. One board foot equals 144 cubic inches of wood — the equivalent of a piece 12 inches wide, 12 inches long, and 1 inch thick. Lumber yards use board feet instead of linear feet because it accounts for both the thickness and width of a board, not just its length.
You enter the thickness, width, and length of a single board along with the quantity you need. The calculator multiplies thickness (in) × width (in) × length (ft) and divides by 12 to get board feet per piece, then multiplies by quantity for the total. The math runs instantly in your browser as you adjust any value.
Board feet per piece = (thickness in inches × width in inches × length in feet) ÷ 12. Multiply that figure by the number of pieces to get your total board footage for an order.
Linear feet only measures length and ignores how thick or wide a board is, so a 2×4 and a 2×12 of the same length would cost the same under a linear-foot system even though the 2×12 contains three times more wood. Board feet corrects for this by capturing total volume, which is why hardwood dealers and mills price by the board foot.
A linear foot measures only the length of a board regardless of its cross-section, while a board foot measures volume based on thickness, width, and length together. Two boards can have the same linear footage but very different board footage if their thickness or width differs.
Use the actual rough-sawn dimensions rather than the nominal size — a rough-sawn board sold as 1 inch thick is typically closer to a true 1 inch, while surfaced (S4S) lumber is thinner after milling. Enter the actual measured thickness and width into the Thickness and Width fields for an accurate board foot count.
Yes — once you have your Total Board Feet result, multiply it by your local price per board foot to estimate total cost. Prices vary widely by species and grade, so check with your supplier for the current per-board-foot rate before finalizing a budget.
Yes, it matters significantly. A nominal 2×4 is actually 1.5 inches by 3.5 inches after milling, so using nominal dimensions instead of actual dimensions will overstate your board footage. Always measure the actual thickness and width of the lumber you're buying or have on hand.
Using actual dimensions of 1.5 in × 3.5 in × 8 ft, a 2×4×8 contains 3.5 board feet. Using nominal dimensions of 2 in × 4 in × 8 ft (common for pricing purposes at some yards), it would calculate to 5.33 board feet, which is why it's important to confirm which convention your supplier uses.
Thickness and width are entered in inches, length is entered in feet, and quantity is the number of individual pieces. The result — Total Board Feet and Board Feet per Piece — is expressed in board feet (bd ft), the standard US lumber measurement unit.
Yes, the board foot formula is identical regardless of species — it is purely a measure of volume. Hardwood is almost always sold by the board foot, while softwood dimensional lumber (like framing studs) is more commonly sold by the linear foot or as a per-piece price, though board feet still applies if you need to compare volume.
List every piece of lumber your project requires with its thickness, width, and length, then run each size through the calculator using the Quantity field for pieces of that same size. Add the Total Board Feet results together across all the different board sizes to get your full project total.
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