Lumber & Woodwork
BD FT Calculator
Quick bd ft totals for dimensional lumber like 2×4, 2×8 and 4×4 using nominal sizes.
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Lumber & Woodwork
Board Foot Calculator
Hardwood and rough-sawn lumber is sold by the board foot. Enter the size of your boards and how many you need to get the total volume and an estimated cost before you visit the lumber yard.
What is a board foot calculator?
A board foot is a unit of lumber volume equal to a piece 1 inch thick, 12 inches wide and 12 inches long — 144 cubic inches. This calculator converts the dimensions of your boards into board feet so you can compare prices and order the right amount.
How does it work?
It multiplies thickness (inches) by width (inches) by length (feet) and divides by 12 to get board feet per piece, then multiplies by the number of boards. If you enter a price, it multiplies the total by that rate. For a shopping list with mixed nominal sizes like 2×4s and 2×8s, use the BD FT Calculator instead.
What information is needed?
- Board thickness in inches (actual, or quarter-sawn designation for rough stock)
- Board width in inches
- Board length in feet
- Number of identical boards
- Price per board foot (optional)
How to use the Board Foot Calculator
- Measure or look up the thickness, width and length of one board.
- Enter how many boards of that size you need.
- Add the yard’s price per board foot if you want a cost estimate.
- Select Calculate. Repeat for each board size and add the totals.
The formula
In plain terms, here is the calculation the tool runs:
Board feet = T × W × L ÷ 12
Total = Board feet × Quantity
- T
- Thickness in inches
- W
- Width in inches
- L
- Length in feet
- 12
- Converts inch-inch-foot to board feet (144 cu in)
Worked example
Example
You are buying four 8/4 walnut boards, each 6 inches wide and 10 feet long, at $4.50 per board foot.
- 2 × 6 × 10 = 120
- 120 ÷ 12 = 10 board feet per board
- 10 × 4 boards = 40 board feet
- 40 × $4.50 = $180.00
You need 40 board feet, costing about $180.
Frequently asked questions
Do I use nominal or actual dimensions?
For rough lumber, use the nominal quarter thickness (8/4 is 2″). For surfaced hardwood, most yards still price on the rough size before planing, so ask your supplier which they use.
How many board feet are in a 2×4×8?
Using nominal size: 2 × 4 × 8 ÷ 12 = 5.33 board feet.
How much extra should I buy?
Add 15–20% for furniture and cabinetry to allow for knots, checks and grain matching. For framing, 10% is usually enough.
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