Board Foot Calculator: Easily Estimate Lumber Volume

Use our board foot calculator to quickly determine the volume of hardwood lumber for your projects. Whether you’re a DIY enthusiast or a professional woodworker, this tool simplifies the process of calculating board feet. If you’re unsure about board feet or how to calculate them, read on for a detailed guide. Otherwise, input your wood dimensions into the calculator and get started!

What Is a Board Foot?

A board foot measures the volume of lumber, unlike square footage, which measures area. It’s a standard unit used when purchasing multiple boards of varying sizes. By definition, one board foot equals one square foot of lumber that is one inch thick.

To convert standard volume units into board feet, use this formula:

1 board foot = 144 cubic inches = 1/12 cubic foot

This makes it easy to estimate the amount of lumber needed for your project.

How to Calculate Board Feet

Calculating board feet is straightforward with this simple formula:

Board feet = length (ft) × width (in) × thickness (in) / 12

Key Notes:

• Length should be in feet.

• Width and thickness should be in inches.

• Ensure consistent units to avoid errors.

For more tools, check out our flooring calculator or decking calculator to plan your next project.

Example: Using the Board Foot Calculator

Let’s walk through an example to calculate the board footage for a lumber purchase:

1. Determine the number of boards: Suppose you need 5 hardwood boards.

2. Specify the dimensions: Each board is 8 feet long, 10 inches wide, and 1.25 inches thick.

3. Apply the formula:

   Board feet = 8 × 10 × 1.25 / 12 = 8.33 BF per board

4. Calculate total board footage:

   5 boards × 8.33 BF = 41.65 BF

5. Estimate cost: If one board foot costs $4.50, the total cost is:

   41.65 × $4.50 = $187.43

For plywood projects, try our plywood calculator to estimate coverage needs.

FAQs

How do you calculate board feet in a log?

To estimate board feet in a log:

• Use a Doyle rule or International ¼-inch rule table.

• Measure the log’s diameter (without bark) in inches at the smaller end.

• Measure the log’s length in feet.

• Refer to the table or use the formula: ((Diameter – 4)/4)² × Length.

This provides an approximate board footage for the log.

How do you measure a board foot?

To measure a board foot:

1. Take a rectangular piece of lumber.

2. Measure its length in feet (round to the nearest decimal).

3. Measure its width and thickness in inches.

4. Multiply the three measurements and divide by 12.

How many board feet are in a 2×4?

The board footage of a 2×4 depends on its length. Here’s a quick reference:

What’s the difference between a board foot and a linear foot?

• Board foot: A measure of volume (length × width × thickness, with length in feet and width/thickness in inches, divided by 12).

• Linear foot: A measure of length, equal to 12 inches (1 foot).

What is board foot insulation?

Board foot insulation measures the volume of spray foam insulation needed to cover a space. Calculate the square footage of the area and multiply by the desired thickness (in inches) to estimate board feet.

How much does a board foot of oak weigh?

On average, a board foot of oak weighs about 3.9 lb (1.77 kg), though this varies (3.08–4.67 lb) depending on the oak species and its growing conditions.

Can you convert square feet to board feet?

Square feet measure area, while board feet measure volume. For example, 320 square feet of lumber with a 1-inch thickness equals 320 board feet. Adjust for thickness to convert accurately.