Board Foot Calculator

What Is a Board Foot?

A board foot (BF) is the standard unit for measuring and pricing lumber volume in the United States. One board foot equals 144 cubic inches of wood — equivalent to a piece that is 1 inch thick, 12 inches wide, and 12 inches long (1″ × 12″ × 12″).

Board feet are the primary pricing unit for hardwood lumber, exotic woods, and rough-sawn softwood. Understanding board feet is essential for comparing lumber prices across different dimensions and species, and for accurately estimating project costs.

The Board Foot Formula

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

Where thickness and width are in inches, and length is in feet. Alternatively, if all dimensions are in inches: BF = (T × W × L) ÷ 144.

Examples:

• 2×4×8′: (2 × 4 × 8) ÷ 12 = 5.33 BF
• 2×6×12′: (2 × 6 × 12) ÷ 12 = 12 BF
• 1×12×10′: (1 × 12 × 10) ÷ 12 = 10 BF
• 4×4×8′: (4 × 4 × 8) ÷ 12 = 10.67 BF

Nominal vs Actual Dimensions

An important distinction when calculating board feet is whether to use nominal or actual dimensions:

• Softwood (framing lumber): Use nominal dimensions. A "2×4" is priced as 2″×4″ even though its actual size is 1.5″×3.5″. This is the industry standard.
• Hardwood (rough lumber): Use actual measured thickness. Hardwood is sold by the "quarter" system: 4/4 (1″), 5/4 (1.25″), 6/4 (1.5″), 8/4 (2″). Width is actual measured width, and random widths are common.
• Planed/surfaced hardwood: Still priced at the rough thickness. An 8/4 board surfaced to 1.75″ is still billed as 8/4 (2″) stock.

Lumber Pricing by Species

Board foot prices vary dramatically by species, grade, and market conditions. Here are typical retail ranges:

• SPF (Spruce-Pine-Fir): $2–$4/BF. Standard framing lumber.
• Douglas Fir: $3–$6/BF. Premium structural lumber, also used for exposed beams.
• Poplar: $3–$5/BF. Affordable hardwood, great for painted projects.
• Red Oak: $4–$8/BF. The most popular cabinet and furniture hardwood in America.
• White Oak: $5–$9/BF. Rot-resistant, used for outdoor furniture and whiskey barrels.
• Hard Maple: $5–$9/BF. Extremely hard, excellent for cutting boards and flooring.
• Cherry: $5–$10/BF. Beautiful grain, darkens with age. Classic furniture wood.
• Walnut: $8–$15/BF. Premium dark hardwood for high-end furniture and woodworking.
• Teak: $15–$30/BF. Extremely weather-resistant, used for outdoor furniture and boat decking.

Board Feet vs Linear Feet

Understanding the difference between these two measurements prevents ordering mistakes:

Linear feetmeasures only length. A 2×4 that is 8 feet long is 8 linear feet, regardless of thickness or width. Home improvement stores typically price dimensional lumber per linear foot or per piece.

Board feetmeasures volume. The same 2×4×8′ contains 5.33 board feet. A 2×12×8′ is also 8 linear feet but contains 16 board feet — three times as much wood. Hardwood lumber yards and sawmills price by the board foot.

Tips for Buying Lumber by the Board Foot

• Calculate your needs before shopping. Make a cut list with every piece you need, then add 15–20% waste factor for defects, sapwood, and cutting waste.
• Buy wider boards for efficiency. Wider boards yield more usable wood per board foot because you lose less to saw kerfs when ripping to final width.
• Check for defects before paying. Knots, checks, and sapwood reduce usable yield from each board. Factor this into your quantity estimate.
• Ask about volume discounts. Many hardwood dealers offer 10–20% discounts on orders over 100 board feet.
• Compare $/BF across species. Sometimes a more expensive species yields more usable wood per BF due to fewer defects, making it cheaper overall.

Common Board Foot Quick Reference

Here are board feet per linear foot for common lumber sizes:

• 1×4: 0.33 BF per foot
• 1×6: 0.50 BF per foot
• 1×8: 0.67 BF per foot
• 1×12: 1.00 BF per foot
• 2×4: 0.67 BF per foot
• 2×6: 1.00 BF per foot
• 2×8: 1.33 BF per foot
• 2×10: 1.67 BF per foot
• 2×12: 2.00 BF per foot
• 4×4: 1.33 BF per foot
• 6×6: 3.00 BF per foot

Frequently Asked Questions

What is a board foot?

A board foot is 144 cubic inches of wood — a piece 1″ thick × 12″ wide × 12″ long. It is the standard pricing unit for hardwood lumber and rough-sawn softwood in the US. Think of it as a 1-foot square of wood that is 1 inch thick.

How do you calculate board feet?

Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12. For a 2×6 that is 8 feet long: (2 × 6 × 8) ÷ 12 = 8 board feet. Our calculator above handles this automatically for any dimensions and quantity.

How much does a board foot of lumber cost?

It depends entirely on species: SPF $2–$4, red oak $4–$8, walnut $8–$15, cherry $5–$10 per board foot. Lumber prices fluctuate with market conditions — check current prices at your local lumber yard or online supplier.

Board feet vs linear feet — what's the difference?

Linear feet measures only length. Board feet measures volume (T × W × L). A 2×6×8′ is 8 linear feet but 8 board feet. A 1×6×8′ is also 8 linear feet but only 4 board feet. Board feet accounts for how much actual wood is in the piece.

Do I use nominal or actual dimensions?

For softwood framing lumber, use nominal dimensions (a "2×4" = 2×4 in the formula). For hardwood rough lumber, use the actual measured thickness (4/4 = 1", 8/4 = 2"). This is the universal industry convention.

How many board feet in a 2×4×8?

(2 × 4 × 8) ÷ 12 = 5.33 board feet per piece. Ten 2×4×8 boards contain 53.3 total board feet.

Related Calculators

• Lumber Calculator — full lumber quantity and cost estimator
• Deck Board Calculator — decking material estimator
• Stud Calculator — wall framing studs and plates

Lumber prices vary by region, supplier, and market conditions. This calculator uses nominal dimensions for board foot calculation (industry standard). For hardwood purchases, confirm pricing convention (nominal vs actual) with your supplier. Always add 15–20% waste to your project estimates.