Board Foot Calculator

A board foot is a unit of measurement for lumber volume. It equals:

• 1 inch thick x 12 inches wide x 12 inches long
• Or 144 cubic inches of wood
• Or 1/12 of a cubic foot

Board feet are the standard unit used by lumber yards and sawmills to price and sell hardwood lumber.

The board foot formula is:

• Board Feet = (Thickness x Width x Length) / 144
• All measurements must be in inches
• If length is in feet, multiply feet by 12 to convert to inches first

For example, a board that is 2" thick x 6" wide x 8 feet long:

• 2 x 6 x 96 (8 feet = 96 inches) = 1,152
• 1,152 / 144 = 8 board feet

Lumber is sold using "nominal" dimensions, but the actual size is smaller due to drying and planing:

• 1x4: Nominal 1" x 4", Actual 3/4" x 3.5"
• 2x4: Nominal 2" x 4", Actual 1.5" x 3.5"
• 2x6: Nominal 2" x 6", Actual 1.5" x 5.5"
• 4x4: Nominal 4" x 4", Actual 3.5" x 3.5"

When buying lumber by the board foot, you typically pay for the nominal dimensions. This calculator uses the dimensions you enter, so use nominal sizes when estimating lumber yard costs.

Board foot pricing is standard for hardwood lumber because:

• It provides a fair way to compare prices across different board sizes
• Hardwood boards come in random widths and lengths
• It accounts for the actual volume of wood you're purchasing
• Exotic or premium species are easily compared dollar-per-board-foot

Softwood (like construction lumber) is typically sold by the linear foot or piece, but board foot calculations are still useful for estimating material needs.

It's wise to add extra material for waste, defects, and mistakes:

• 10-15%: For straightforward projects with minimal cuts
• 15-20%: For projects with many angled or complex cuts
• 20-25%: For rough lumber that needs significant milling
• 25%+: For lumber with known defects or for beginners

Calculate your total board feet first, then multiply by your waste factor (e.g., 1.15 for 15% waste).