What is a board foot?
A board foot is a volume-based lumber measurement unit equal to 144 cubic inches, the volume of a piece 1 inch thick, 12 inches wide, and 1 foot long. The National Hardwood Lumber Association (NHLA), US sawmills, and hardwood dealers across North America use the board foot (abbreviated BF or Bd. Ft.) as the standard pricing unit for rough and surfaced hardwood lumber.
Board feet measure volume rather than length because hardwood varies in thickness and width within a single order. A woodworker buying 50 linear feet of 4/4 walnut gets a different amount of wood than 50 linear feet of 8/4 walnut, even though the linear measurement matches. The volume-based board foot captures thickness, width, and length in one figure, so lumber yards can price mixed boards consistently. Furniture makers, cabinet shops, and DIY woodworkers use board feet for dining tables, bookshelves, cutting boards, and other mixed-dimension projects.
Board foot formula
The board foot formula is (Thickness × Width × Length) ÷ 12 when length is measured in feet, or (Thickness × Width × Length) ÷ 144 when all three dimensions are in inches. Both formulas produce the identical result because 12 inches equals 1 foot.
Formula 1 (length in feet): (T × W × L) ÷ 12 = Board Feet
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Formula 2 (length in inches): (T × W × L) ÷ 144 = Board Feet
Three variables go into the calculation: thickness (T) measured in inches, width (W) measured in inches, and length (L) measured in feet or inches depending on the formula. Lumber yards apply Formula 1 for dimensional lumber sold by the foot, such as 2x4s and 2x6s. Craftsmen apply Formula 2 for short hardwood cut-offs and shop stock where every inch counts. Our board foot calculator does the math for you.
How to calculate board feet step by step
Calculating board feet takes 5 steps for any lumber order.
- Measure the thickness in inches, the width in inches, and the length in feet with a tape measure or digital caliper.
- Multiply thickness × width × length to get the raw volume figure.
- Divide the result by 12 when length is in feet, or by 144 when length is in inches.
- Multiply the single-board board foot value by the total number of boards in the order.
- Add a waste factor of 10% to 15% to cover knots, checks, and trim cuts during milling.
Board foot calculation examples
The same formula handles every common dimensional lumber size: 2x4, 2x6, 2x8, 1x6, and 4x4. The table below applies Formula 1 to six standard lumber pieces at 8-foot and 10-foot lengths. Nominal sizes (2x4, 2x6) are the pre-surfaced dimensions printed on the board tag. Actual sizes (1.5" × 3.5" for a 2x4) are the planed dimensions. Lumber yards calculate by nominal size for board foot purposes.
| Lumber Size | Length | Formula | Board Feet |
|---|---|---|---|
| 2x4 | 8 ft | (2 × 4 × 8) ÷ 12 | 5.33 BF |
| 2x4 | 10 ft | (2 × 4 × 10) ÷ 12 | 6.67 BF |
| 2x6 | 8 ft | (2 × 6 × 8) ÷ 12 | 8.00 BF |
| 2x8 | 10 ft | (2 × 8 × 10) ÷ 12 | 13.33 BF |
| 1x6 | 8 ft | (1 × 6 × 8) ÷ 12 | 4.00 BF |
| 4x4 | 8 ft | (4 × 4 × 8) ÷ 12 | 10.67 BF |
Board feet vs linear feet vs square feet
Board feet, linear feet, and square feet measure volume, length, and surface area. Board feet apply to hardwood and rough lumber priced by volume, linear feet apply to dimensional framing lumber priced per running foot, and square feet apply to plywood, OSB, and hardwood flooring priced by coverage.
| Unit | What It Measures | Typical Use |
|---|---|---|
| Board Feet | Volume (144 cubic inches) | Hardwood lumber, rough-sawn stock, furniture-grade boards |
| Linear Feet | Length along one dimension | 2x4 framing, trim, molding, railings |
| Square Feet | Surface area (width × length) | Plywood, OSB, hardwood flooring, drywall |
The three units overlap for dimensional lumber such as a 2x4. It carries a linear foot price at big-box retailers like Home Depot and Lowe's, and a board foot price at hardwood dealers. Homeowners shopping framing lumber at Home Depot see linear foot pricing, while woodworkers ordering walnut from a specialty mill see board foot pricing. Most confusion comes when a single project mixes dimensional framing (linear feet), hardwood trim (board feet), and plywood sheathing (square feet).
The board foot formula works cleanly for one or two pieces, but real lumber orders rarely stop there. A furniture project might include 40 boards in three different dimensions, and a deck frame regularly runs past 100 pieces. For anything beyond a handful of boards, use our board foot calculator to enter your lumber list and get total board feet, linear feet, and estimated cost.
Board feet chart for common lumber sizes
The chart below lists board feet per linear foot and total board feet at 8-ft, 10-ft, 12-ft, and 16-ft lengths for 9 common nominal lumber sizes: 1x4, 1x6, 1x8, 2x4, 2x6, 2x8, 2x10, 2x12, and 4x4.
| Nominal Size | Actual Size (in) | BF per Linear Foot | BF @ 8 ft | BF @ 10 ft | BF @ 12 ft | BF @ 16 ft |
|---|---|---|---|---|---|---|
| 1x4 | 0.75 × 3.5 | 0.333 | 2.67 | 3.33 | 4.00 | 5.33 |
| 1x6 | 0.75 × 5.5 | 0.500 | 4.00 | 5.00 | 6.00 | 8.00 |
| 1x8 | 0.75 × 7.25 | 0.667 | 5.33 | 6.67 | 8.00 | 10.67 |
| 2x4 | 1.5 × 3.5 | 0.667 | 5.33 | 6.67 | 8.00 | 10.67 |
| 2x6 | 1.5 × 5.5 | 1.000 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2x8 | 1.5 × 7.25 | 1.333 | 10.67 | 13.33 | 16.00 | 21.33 |
| 2x10 | 1.5 × 9.25 | 1.667 | 13.33 | 16.67 | 20.00 | 26.67 |
| 2x12 | 1.5 × 11.25 | 2.000 | 16.00 | 20.00 | 24.00 | 32.00 |
| 4x4 | 3.5 × 3.5 | 1.333 | 10.67 | 13.33 | 16.00 | 21.33 |
Board foot pricing and how lumber is sold
Lumber yards and hardwood dealers price boards by board feet for rough and surfaced hardwood, and by linear foot for dimensional softwood framing. A 4/4 (four-quarter, 1-inch nominal thickness) red oak board priced at $6.50 per BF costs $34.67 for an 8-ft 1x8 board. Pricing varies by species, grading, and retailer type (big-box retailers versus specialty mills). A precise board foot estimate keeps a project on budget.
- Board foot pricing sets a per-BF rate that covers mixed dimensions within a single order, which matters for furniture makers buying 4/4, 6/4, and 8/4 stock simultaneously.
- Nominal vs actual dimensions affect the billing. A 2x4 bills at 0.667 BF per linear foot using nominal 2" × 4", even though the actual planed size measures 1.5" × 3.5".
- Hardwood grading under the NHLA system (FAS, Select, #1 Common, #2 Common) adjusts the BF price. FAS walnut trades for 30% to 50% more per BF than #1 Common walnut.
- Species variation shifts the BF rate. Domestic poplar averages $3 per BF, domestic walnut averages $9 per BF, and tropical species such as Peruvian bloodwood exceed $18 per BF.
- Volume tiers divide DIY and contractor pricing. Contractors ordering 500+ BF receive tiered discounts of 10% to 20% at yards including J. Gibson McIlvain, Bell Forest Products, and Irion Lumber.
When to use board feet vs linear feet
Each unit applies to specific lumber and sheet good scenarios.
- For hardwood and rough lumber, use board feet. Species such as walnut, cherry, hard maple, and white oak sold at hardwood dealers price exclusively per BF.
- For dimensional framing lumber, use linear feet. Studs, joists, and rafters such as 2x4x8 and 2x6x10 price per running foot at Home Depot and Lowe's.
- For decking projects, use linear feet for the deck boards themselves and square feet for total deck surface. Our deck board calculator converts deck dimensions into deck board count, linear feet, and waste-adjusted quantity estimates for pressure-treated, cedar, or composite boards.
- For hardwood flooring, use square feet for coverage and board feet for raw stock. Hardwood flooring ships by carton in square feet. The underlying rough lumber ships in board feet. Our flooring calculator determines the square footage, waste factor, and carton count for oak, maple, or hickory flooring.
- For plywood and sheet goods, use square feet. A 4x8 plywood sheet covers 32 square feet, priced per sheet rather than per BF.