How to Easily Calculate Board Feet

The first time you go to the lumberyard can be a little overwhelming if you don’t know what you’re doing.  Even if you think you know what you’re doing, all the different species of lumber, the different dimensions of the lumber, different locations within the lumberyard, etc. can seem daunting for finding the perfect piece for your project.  With just a little bit of simple math, one area where you can be totally confident is calculating the cost of your chosen board.

Most home centers sell lumber by the linear foot, which means that the price of the board is determined by the length of the board. You pay a little extra for the convenience of a home center and you likely aren’t getting the best piece of lumber.  The lumberyard, on the other hand, sells their lumber by the board foot.  A board foot takes into consideration the thickness, width and length of a board.  There are several apps board foot calculator apps to help you figure out how many board feet are in your chosen piece, but all you need to remember is one simple formula and you can calculate board feet anywhere. 

Board feet = Length x Width x Depth

This formula means that a board one inch thick by twelve inches wide by twelve inches long is equal to one board foot.  Input into the simple formula it’s easy to see.

1 Board feet = 12” x 12” x 1”

Now let’s try another calculation.  Let’s take a board that’s 1” thick by 16 inches wide by 5 feet long. Can you tell me how many board feet that would be? Simple right: 1” x 16” x 60” = 720 in.3 / 144 = 6.67 board feet.

Another example:  A board is 2 inches thick by 8 inches wide by 18 feet long.  I know what you’re thinking, this is going to be an expensive board.  True, but it’s still easy to calculate.  2” x 8” x 216” (12 x 18) = 3,456 in.3 / 144 = 24 board feet.  If that board is $9.99 per bf, you can confidently know that it will cost $240 before any tax.

lumber yard

This is a simple rule and the math can be done on the calculator in your phone. You can even ask Siri to do it for you.  Make sure you bring your tape measure that you know is reliable to the lumberyard.  You should measure the board yourself so you can ensure the accuracy.  There you have it, the easy way to calculate board feet.  Now, go out and build something!