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Board Foot Calculator

Created by Bogna Szyk
Reviewed by Małgorzata Koperska, MD and Jack Bowater
Last updated: Jan 18, 2024

This board foot calculator allows you to quickly estimate the volume of hardwood lumber you want to buy. If you're unsure how to calculate board feet or what a board foot is, scroll down for more in-depth information. Otherwise, simply type the dimensions of a wood piece into this board foot calculator!

What is a board foot?

Unlike square footage, which measures area, board footage measures volume. You use it when purchasing multiple boards of lumber in various sizes.

By definition, one board foot of lumber is one square foot that is one-inch thick. If you would like to convert regular volume units into board feet, use the following relation:

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

How to calculate board feet?

Surprisingly, the calculations are extremely easy! All you need to do is use the board foot formula below:

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

Pay special attention to the units! The length of the wooden board should be expressed in feet, while the width and thickness – in inches.

💡 You might also be interested in our flooring calculator and decking calculator.

Using the lumber calculator: an example

Let's assume you want to use this board foot calculator to determine how much you should pay for a few hardwood pieces.

  1. Decide on the number of pieces you want to purchase. Let's assume it's five wooden boards.

  2. Choose the dimensions of the boards. For example, a piece of hardwood can be 8 feet long, 10 inches wide, and 1.25 inches thick.

  3. Substitute these numbers into the board foot formula to find the board footage per piece:

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

    board feet = 8 × 10 × 1.25 / 12

    board feet = 8.33 BF

  4. Now, multiply this result by the number of pieces to obtain the total board footage of your purchase:

    5 × 8.33 = 41.67 BF

  5. Finally, you can multiply this value by the price per board foot to determine the total cost of your purchase. Assuming one board foot of lumber costs $4.15, then:

    cost = 41.67 × $4.15 = $172.92

💡 If you need to cover walls or flooring in plywood, check out our plywood calculator.


How do you calculate the board feet in a log?

To calculate the board feet in a log, do the following:

  1. Find either a Doyle rule or the International ¼-inch rule table.

  2. Measure the diameter of the shorter end of the log (not including bark) in inches.

  3. Measure the length of the log in feet.

  4. Look up where the two values meet on the table.

  5. Alternatively, use the equation ((Diameter - 4)/4)² × Length, where the units are those you measured.

  6. The answer is an estimate of the board feet in a log.

How do you measure a board foot?

To measure a board foot:

  1. Take a rectangular piece of lumber.

  2. Measure the length of it in feet, rounding to the nearest decimal place.

  3. Measure the width in inches. You can also measure in feet; if so, don’t divide by 12 in step 5.

  4. Measure the thickness in inches.

  5. Multiply all three numbers together and divide by 12.

How many board feet are in a 2x4?

Length of 2x4 (ft)

Number of board feet





















What is the difference between a board foot and a linear foot?

The main difference between a board foot and a linear foot is that a board foot is a measure of volume, whereas a linear foot is a measure of length.

A board foot is generally used for lumber and is the multiplication of its width in feet, length in feet, and thickness in inches. A linear foot is a straight line 12 inches (1 foot) in length.

What is a board foot insulation?

Board foot insulation is a measurement of how much volume spray foam insulation can cover.

A board foot is a volume of 1 ft × 1 ft × 1 in, so estimate the volume you need to fill before buying your spray foam insulation by finding the square footage of the space.

A board foot is also a common unit of measure for lumber in the USA and Canada.

How much does a board foot of oak weigh?

A board foot of oak weighs anywhere between 3.08-4.67 lb (1.42-2.12 kg), but on average, one weighs 3.875 lb (1.77 kg).

That is because the density of Oak can vary from 37-56 lb/ft³ (600-900 kg/m³), depending on the variety and location it was grown.

How many board feet are there in 320 square feet?

There are no board feet in 320 square feet, as board feet is a measure of volume and square feet is a measure of area. However, for an area that is 320 square feet with a depth of 1 inch, there are 320 board feet present.

Bogna Szyk
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