Board Foot Calculator

Created by Bogna Szyk
Reviewed by Małgorzata Koperska, MD and Jack Bowater
Last updated: Feb 10, 2021

This board foot calculator allows you to quickly estimate the volume of hardwood lumber you want to buy. If you're not sure how to calculate board feet or what a board foot is, scroll down for some 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, the board footage is a measurement of volume. It is used 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.

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

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

5 * 8.33 = 41.67 BF

  1. 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,

cost = 41.67 * $4.15 = $172.92

You will pay approximately $170.

To calculate arc length without radius, you need the central angle and the sector area:

  1. Multiply the area by 2 and divide the result by the central angle in radians.

  2. Find the square root of this division.

  3. Multiply this root by the central angle again to get the arc length.

  4. The units will be the square root of the sector area angle.

  5. Check your result with Omni Calculator.

Or the central angle and the chord length:

  1. Divide the central angle in radians by 2 and perform the sin function on it.
  2. Divide the chord length by double the result of step 1. This gives you the radius.
  3. Multiply the radius by the central angle to get the arc length.
  4. Check your result with Omni Calculator.


How do you calculate the board feet in a log?

  1. Find either a Doyle rule or the International 1/4-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 x Length, where the units are those you measured it.
  6. The answer is an estimate of the board feet in a log.

How do you 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 Number of board feet
6 4
8 51/3
10 62/3
12 8
14 91/3
16 102/3
18 12
20 131/3
22 142/3
24 16

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 that is 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 1 ft x 1 ft x 1 in, so estimate the volume you need to fill before buying your spray foam insulation buy 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). This is because the density of Oak can vary from 37 - 56 lb / ft3 (0.6 - 0.9 103 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
No. of pieces
board feet
$/ board foot
Total cost
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