What is a board foot and why does it matter?
A board foot is the standard unit of measurement used in the lumber and woodworking industry to express the volume of lumber. One board foot equals a piece of wood that is one inch thick, 12 inches wide, and 1 foot long — or 144 cubic inches of wood in any equivalent shape. Because hardwood lumber and rough stock come in various sizes of width and thickness, pricing and ordering by the board foot gives buyers and suppliers a consistent unit of measurement regardless of the individual board dimensions.
Lumber is typically priced per board foot at hardwood dealers, sawmills, and specialty wood retailers. Knowing how to use board feet correctly helps you compare prices across wood species — from maple to oak — and across wood products with different thicknesses and lengths without confusion.
The board foot formula explained
The board foot formula converts the three physical dimensions of a board into a single volume figure:
Board foot formula
BF = (Thickness″ × Width″ × Lengthft) ÷ 12
Example A: A board 1 inch thick, 6 inches wide, 8 feet long → (1 × 6 × 8) ÷ 12 = 4 BF
Example B: A board 2 inches thick, 10″ wide, 12 ft × 3 pieces → (2 × 10 × 12) ÷ 12 × 3 = 60 BF
All-inches variant: Divide by 144 when all three inputs are in inches — same result.
The calculation works for any combination of width and thickness — a board that is 1.5 inches thick and 4″ wide at 8 feet length in feet yields (1.5 × 4 × 8) ÷ 12 = 4 BF. Decimal and fraction inputs are both supported in the calculator.
How to use this board foot calculator
Use our board foot calculator to determine the total board footage for any list of boards in four steps:
- 1
Enter thickness and width
Input the thickness and width of the board in inches. For surfaced lumber, use actual dimensions — a nominal 2×4 measures 1.5" thick and 3.5" wide after milling. For rough hardwood, nominal thickness is usually closer to what you receive.
- 2
Enter the board length
Enter the length in feet. A board that is 8 feet long is entered as 8. Mixed units are supported — the calculator converts automatically. Length in feet is the most common input format when calculating board feet.
- 3
Set the number of pieces
Enter the quantity — the number of pieces at that size. The calculator multiplies the single-board BF by the piece count to give total board feet for that row. Add multiple rows for different board dimensions in the same estimate.
- 4
Add price per board foot for cost estimation
Enter the cost per board foot from your supplier to generate a total cost alongside the volume figure. Cost estimation helps compare pricing between wood species and suppliers before committing to an order.
Understanding the calculator outputs
- Total board feet
- The primary volume measurement — the sum of BF across all board rows. This is the figure your supplier uses to price hardwood lumber and rough stock.
- Board footage per piece
- The individual BF contribution of one board. Useful for comparing wood dimensions across species or grades before scaling up to the full order quantity.
- Linear feet
- Total end-to-end board length across all pieces. Used when lumber is priced by the linear foot — common for trim, moulding, and joinery stock.
- Cubic volume
- The full three-dimensional volume in cubic feet or cubic inches — a unit of volume that bridges board feet to metric or cubic measurements when needed.
- Face area
- The flat surface area in square feet if all boards were laid face-up. Useful for estimating coverage of a surface such as a tabletop, panel, or deck.
- Total cost
- Price per board foot × total board feet. Optional — enter cost per board foot from your supplier to generate a cost estimation for the full material list.
Nominal vs actual lumber dimensions
Nominal sizing is the trade name for lumber before drying and surfacing. Actual wood dimensions are smaller. For calculating board feet accurately, always confirm which dimension you are working from:
| Nominal size | Actual size | BF at 8 ft (nominal) | BF at 8 ft (actual) |
|---|---|---|---|
| 1 × 4 | ¾" × 3½" | 2.67 | 1.75 |
| 1 × 6 | ¾" × 5½" | 4.00 | 2.75 |
| 2 × 4 | 1½" × 3½" | 5.33 | 3.50 |
| 2 × 6 | 1½" × 5½" | 8.00 | 5.50 |
| 2 × 8 | 1½" × 7¼" | 10.67 | 7.25 |
Using nominal dimensions overstates the actual lumber volume. For hardwood and rough-sawn stock, nominal thickness is often closer to actual — verify with your supplier before calculating board feet.
Frequently asked questions
- What exactly is one board foot?
- One board foot is a unit of volume equal to 144 cubic inches — the volume of a piece of wood that is one inch thick, 12 inches wide, and one foot long. It is the standard unit of measurement used to price and sell hardwood lumber, rough stock, and many specialty wood products.
- How do I calculate board feet?
- Use the board foot formula: (Thickness in inches × Width in inches × Length in feet) ÷ 12. For example, a board 2 inches thick, 6 inches wide, and 8 feet long equals (2 × 6 × 8) ÷ 12 = 8 BF. Multiply by the number of pieces for a total. Use our board foot calculator to determine the total instantly across multiple board sizes.
- Should I use nominal or actual dimensions?
- For surfaced framing lumber, actual dimensions give a more accurate board footage result because nominal sizes overstate the real wood volume. For rough hardwood lumber purchased by the board foot, nominal thickness is often what the sawmill uses to price the stock — check with your supplier to confirm which measurement they apply.
- How do I convert board feet to linear feet?
- Linear feet measure end-to-end length only; board feet measure volume. To convert, divide total board feet by (thickness × width ÷ 12). A 2" × 6" board with 10 BF = 10 ÷ (2 × 6 ÷ 12) = 10 linear feet. The calculator outputs both figures simultaneously so you can use whichever measurement your supplier requires.
- How do I estimate cost using the board foot calculator?
- Enter the price per board foot from your supplier alongside the board dimensions. The calculator multiplies the total board feet by the cost per board foot to give a total cost for the full material list. This makes it easy to compare pricing across wood species or between suppliers quoting different price per board foot rates.
- Does the calculator account for waste?
- Add a waste percentage on top of your calculated total board feet — typically 5–10% for straight cuts and clean stock, 10–15% for complex joinery or boards with significant defects. Hardwood lumber with natural edges and figure may need a higher waste allowance depending on the project requirements.
Calculate board feet for your next project
Use our board foot calculator to determine the total board footage, linear feet, and cost for any lumber order. Enter your board dimensions, set the number of pieces, add a price per board foot, and get a complete material estimate you can take to your supplier — whether you are measuring lumber for a furniture build, a deck, or a full hardwood order.