What is the difference between nominal and actual lumber dimensions?

Nominal dimensions are the sizes of lumber before it is dried and planed (e.g., a 2x4). The actual dimensions are the finished sizes, which are smaller (e.g., a 2x4 is actually about 1.5" x 3.5"). The board foot calculation is traditionally based on the nominal dimensions of rough-sawn lumber.

Why is the formula divided by 12?

The standard formula for board feet uses thickness in inches, width in inches, and length in feet. To make the units consistent and calculate the volume correctly in terms of 'board feet' (which is 144 cubic inches), the formula is divided by 12. The full formula is (T' x W' x L') / 144, but the simplified version (T' x W' x L ft) / 12 is more commonly used and mathematically equivalent.

How is board footage used for pricing?

Hardwoods and specialty softwoods are often sold by the board foot. To find the total cost of your lumber, you would multiply the total board feet calculated by the price per board foot charged by your lumber supplier.

Lumber Calculator

Estimate the board feet for your lumber needs.

Lumber Dimensions

Thickness (in)

Width (in)

Length (ft)

Quantity

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About the Lumber Calculator

Understand the board foot and how to measure lumber for your projects.

What is a Board Foot?

A board foot is a unit of measurement for the volume of lumber, primarily used in the United States and Canada. It represents the volume of a piece of wood that is one foot long, one foot wide, and one inch thick. So, a 1-inch thick, 12-inch wide, and 1-foot long board is exactly one board foot. This standard unit allows for a consistent way to measure and price lumber, especially hardwoods, regardless of the board's specific shape.

How to Use This Calculator

To calculate the board feet of your lumber, enter the nominal thickness (in inches), width (in inches), and length (in feet) of a single piece of wood. Then, input the total quantity of pieces you have. The calculator applies the standard industry formula to determine the board feet for one piece and then multiplies that by the quantity to give you the total board feet for your entire project. This makes it easy to purchase the right amount of material and budget accordingly.

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

Frequently Asked Questions

Practical Applications

Calculating board feet is essential for many woodworking and construction projects:

Woodworking: Accurately estimate the amount of hardwood needed for furniture projects like tables, chairs, bookshelves, and cabinets.
Construction: Calculate the lumber required for framing walls, building roof structures, or laying down flooring and decking.
Cost Estimation: Since many lumberyards sell wood by the board foot, this calculation is crucial for accurately budgeting your project and comparing prices from different suppliers.
Project Planning: Ensures you buy the correct amount of wood for your project, which helps minimize waste and avoids the inconvenience of having to make extra trips to the store for more material.