Board Foot

What is a Board Foot?

A board foot is a unit of lumber measurement that represents volume. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide, and 12 inches long - essentially 144 cubic inches of wood.

Board feet are primarily used for measuring and pricing hardwood lumber, rough lumber, and specialty wood products.

Board Foot Formula

Basic Calculation

Board Feet = (Thickness in inches) × (Width in inches) × (Length in inches) ÷ 144

Alternative Formula

Board Feet = (Thickness in inches) × (Width in inches) × (Length in feet) ÷ 12

Calculating Examples

Example 1: Standard 2×4×8

• Thickness: 1.5 inches (actual dimension)
• Width: 3.5 inches (actual dimension)
• Length: 8 feet (96 inches)
• Board Feet = 1.5 × 3.5 × 96 ÷ 144 = 3.5 board feet

Example 2: Hardwood Plank

• Thickness: 1 inch
• Width: 6 inches
• Length: 10 feet (120 inches)
• Board Feet = 1 × 6 × 120 ÷ 144 = 5 board feet

Example 3: Large Beam

• Thickness: 6 inches
• Width: 8 inches
• Length: 12 feet (144 inches)
• Board Feet = 6 × 8 × 144 ÷ 144 = 48 board feet

When Board Feet Are Used

Hardwood Lumber

Most hardwood is sold by the board foot rather than by piece:

• Oak, maple, cherry, walnut
• Exotic species and imported woods
• Custom millwork materials
• Reclaimed and specialty lumber

Rough Lumber

Unfinished lumber before planing and surfacing:

• Rough-sawn dimensional lumber
• Live-edge slabs and beams
• Custom milling projects

Large Timbers

Heavy structural members:

• Glulam beams and posts
• Timber frame construction
• Custom architectural elements

Board Foot vs. Linear Foot

Board Foot

• Measures volume (thickness × width × length)
• Used for hardwood and specialty lumber
• Pricing varies by wood species and grade
• Accounts for the actual amount of wood material

Linear Foot

• Measures only length
• Used for trim, molding, and standard dimensional lumber
• Simpler pricing structure
• Doesn't account for thickness variations

Lumber Grades and Pricing

Hardwood Grades

• FAS (Firsts and Seconds): Highest grade, $4-$20+ per board foot
• Select: Good quality, $3-$15+ per board foot
• No. 1 Common: Standard grade, $2-$10+ per board foot
• No. 2 Common: Economy grade, $1-$6+ per board foot

Factors Affecting Price

• Wood species (pine vs. walnut vs. exotic woods)
• Grade and quality of lumber
• Moisture content (kiln-dried vs. air-dried)
• Market conditions and availability

Ordering Lumber by Board Feet

Planning Your Order

1. Calculate total board feet needed for project
2. Add 10-20% waste factor for cuts and defects
3. Specify wood species, grade, and dimensions
4. Consider lumber lengths available from supplier

Working with Lumber Yards

• Specify "board feet" when requesting quotes
• Ask about grade options and pricing tiers
• Inquire about bulk discounts for large orders
• Verify actual dimensions vs. nominal sizes

Conversion Tips

From Pieces to Board Feet

If you know you need specific pieces:

1. Calculate board feet for each piece size
2. Multiply by number of pieces needed
3. Add waste factor for final order quantity

From Board Feet to Pieces

If lumber yard quotes in board feet:

1. Divide total board feet by board feet per piece
2. This tells you how many pieces you're getting
3. Verify this meets your project needs

Common Mistakes

Using Nominal Dimensions: Always use actual lumber dimensions for accurate calculations.

Forgetting Waste Factor: Hardwood often has defects requiring extra material.

Mixing Units: Don't confuse board feet with linear feet or square feet.

Ignoring Grade Requirements: Higher grades cost more but may be necessary for visible work.

Practical Applications

Cabinet Making

Calculate board feet needed for face frames, panels, and doors based on cutting diagrams.

Flooring Projects

Determine hardwood flooring needs, though flooring is often sold by square foot.

Timber Framing

Calculate large beam and post requirements for structural projects.

Furniture Building

Estimate material costs for custom furniture and woodworking projects.