Board Foot Calculator

How to Use the Board Foot Calculator

1. Add a separate board row for each different size in your project.
2. Enter actual thickness, width, length, and the number of identical pieces. You can mix inches, feet, feet plus inches, and metric units.
3. Choose a nominal preset if useful. The calculator loads common actual surfaced dimensions, which you can still edit.
4. Select a waste allowance based on your cut plan and material quality.
5. Optionally enter your supplier's price per board foot to see estimated costs.

The project summary updates as you type. Invalid or incomplete rows are not included in the total.

What Is a Board Foot?

A board foot is a unit of lumber volume, not just length or area. One board foot equals 144 cubic inches. A piece measuring 1 inch thick by 12 inches wide by 12 inches long has a volume of one board foot.

Because the unit accounts for all three dimensions, it is commonly used to price hardwood and rough-sawn lumber of varying thicknesses and widths.

Board Foot Formula

When thickness and width are in inches and length is in feet, use:

For several identical pieces, multiply by quantity. This calculator converts other supported units to inches internally, keeps full precision through the calculation, and rounds only the displayed result.

Board Foot Calculation Example

Suppose you need ten boards that are 2 inches thick, 6 inches wide, and 8 feet long:

2 × 6 × 8 × 10 ÷ 12 = 80 board feet

With a 10% waste allowance, add 8 BF, making the recommended purchase amount 88 BF.

Calculating Lumber Cost

Multiply raw board feet by the price per board foot for the base lumber cost. For example, 80 BF at $4.50 per BF costs $360 before waste. If the purchase amount is 88 BF after waste, the estimated total becomes $396.

Currency selection changes the symbol and formatting only. It does not convert prices or retrieve exchange rates.

Accounting for Lumber Waste

Waste covers saw kerfs, end checks, knots, defects, milling loss, cutting mistakes, and parts that must match in color or grain. A simple cut list using clean stock may need 5–10%. Projects with complex joinery, irregular boards, or selective grain matching often justify 15–20% or a project-specific allowance.

Common Lumber Size Reference

Nominal labels such as 2×4 identify a size category. Surfacing and drying usually make the finished board smaller. The reference below shows common actual dimensions for surfaced dimensional softwood in North America.

Actual dimensions can vary with lumber type, surfacing, moisture, local standards, and supplier. Measure the material or check the seller's specification when accuracy matters.

Board Foot vs Linear Foot

A linear foot measures only length. A 1-foot length is one linear foot whether it is a thin strip or a large beam. Board feet measure volume, so thickness and width change the result. Use linear feet for length-based purchasing and board feet when lumber is sold by volume.

Board Foot vs Square Foot

A square foot measures surface area. It is useful for flooring coverage, panel faces, and finishes. A board foot adds thickness to that area, making it a volume measurement. Twelve square feet of 1-inch-thick material equals 12 board feet, but changing thickness changes board feet without changing surface area.

Board Foot and Lumber Buying Tips

• Confirm whether a price applies to rough, surfaced, or nominal dimensions.
• Measure random boards when sizes vary across a stack.
• Build a cut list before choosing the waste percentage.
• Allow extra material for defects, grain direction, color matching, and milling.
• Keep calculation precision during planning, then round your purchase upward according to how the supplier sells stock.

Frequently Asked Questions