Board Foot Calculator

Board Foot Calculator for Lumber

A board foot calculator helps you determine the volume of lumber needed for your project. Board feet is the standard unit for buying hardwood lumber and accounts for thickness, width, and length. Essential for accurate material estimates and cost calculations.

What is a Board Foot?

A board foot is a unit of volume for lumber:

• 1 board foot = 1 inch thick × 12 inches wide × 12 inches long
• Equals 144 cubic inches
• Standard unit for hardwood lumber pricing
• Accounts for all three dimensions (thickness, width, length)

Board Foot Formula

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

Common Examples

1×6×8 Board

Thickness: 1", Width: 6", Length: 8'

Board feet: (1 × 6 × 8) / 12 = 4 board feet

2×4×10 Board

Thickness: 2", Width: 4", Length: 10'

Board feet: (2 × 4 × 10) / 12 = 6.67 board feet

1×12×12 Board

Thickness: 1", Width: 12", Length: 12'

Board feet: (1 × 12 × 12) / 12 = 12 board feet

Board Feet vs Linear Feet

Board Feet (Volume)

Accounts for thickness, width, and length. Standard for hardwood lumber. Example: 1×6×8 = 4 board feet.

Linear Feet (Length Only)

Only measures length. Used for softwood construction lumber. Example: 8 linear feet (regardless of size).

Common Lumber Sizes

Hardwood (Sold by Board Feet)

• 4/4 (1"): Rough thickness, finishes to ~3/4"
• 5/4 (1.25"): Finishes to ~1"
• 6/4 (1.5"): Finishes to ~1.25"
• 8/4 (2"): Finishes to ~1.75"

Note: Hardwood is sold in quarters (4/4, 5/4, etc.) representing rough thickness.

Softwood (Sold by Linear Feet or Pieces)

• 2×4: Actually 1.5" × 3.5" (nominal vs actual)
• 2×6: Actually 1.5" × 5.5"
• 2×8: Actually 1.5" × 7.25"
• 1×4: Actually 0.75" × 3.5"

Note: Softwood dimensions are nominal (name) vs actual (size). Use actual dimensions for board foot calculations.

Pricing by Board Feet

Hardwood lumber is typically priced per board foot:

• Common hardwoods: $3-8 per board foot
• Premium hardwoods: $8-15+ per board foot
• Exotic woods: $15-50+ per board foot

Example: 50 board feet at $5/bf = $250

Calculating Project Needs

Step-by-Step

1. List all pieces: Thickness, width, length, quantity
2. Calculate each: Use board foot formula
3. Add together: Sum all board feet
4. Add waste: Add 10-20% for cuts and mistakes
5. Calculate cost: Multiply by price per board foot

Waste and Overage

Always add extra lumber for:

• Cuts and waste: 10-15% for simple projects
• Complex projects: 20-30% for intricate work
• Defects: Knots, splits, warping
• Matching grain: Extra needed for grain matching

Example Project Calculation

Small Table Top

Need: 4 pieces of 1×6×3'

Board feet per piece: (1 × 6 × 3) / 12 = 1.5 bf

Total: 1.5 × 4 = 6 board feet

With 15% waste: 6 × 1.15 = 6.9 board feet

Buy: 7-8 board feet

Converting Board Feet to Cubic Feet

1 board foot = 1/12 cubic foot (0.0833 cubic feet)

To convert: Board feet ÷ 12 = Cubic feet

Example: 12 board feet = 1 cubic foot

Tips for Buying Lumber

1. Calculate accurately: Measure all pieces needed
2. Add waste: 10-20% extra for cuts
3. Check actual dimensions: Nominal vs actual sizes differ
4. Inspect boards: Check for defects before buying
5. Buy extra: Better to have leftover than run short
6. Understand pricing: Know if priced by board foot or linear foot

Common Hardwood Species

• Oak: $4-8/bf, durable, common
• Maple: $5-10/bf, hard, light color
• Cherry: $6-12/bf, beautiful grain, darkens with age
• Walnut: $8-15/bf, premium, dark rich color
• Pine: $2-5/bf, softwood, affordable

Nominal vs Actual Dimensions

Lumber is sold by nominal (name) dimensions, but actual dimensions are smaller:

For board foot calculations, use actual dimensions, not nominal.