Lumber Lingo: Understanding “Board Feet”

When building a project from wood, it makes sense that you would need to know some special jargon. After all, as you estimate the amount of materials you’ll need, you’re essentially describing an abstract three-dimensional project that still only exists in your mind. How you express what you need is an important factor in making sure you estimate the overall cost correctly and end up with the right amount of materials.

One of the most commonly misused phrases we’ve heard at our lumber stores is the term “board feet.” In this article, we’ll break down exactly what that means (it might not be what you think it is!), how to calculate it, and when is the right time to use it.

But first, let’s start with some definitions of things that aren’t board feet – but are sometimes mistaken for such.

Linear feet

Simply put, the term “linear feet” is a measurement of length. That can be the length of the amount of fencing you want to install, or the length of an individual board. You’ll use this term when estimating the amount and cost of materials you’ll need for a project.

Be clear about what “linear feet” is referring to as you scope out your project. Calculating the cost of a “fence that is 100 linear feet long” is very different than discussing a “board that costs 10 cents per linear foot.” If you’re determining cost and materials on your own, ask the team at the lumber store to double check your work. They’ll make sure you’re not drastically off-base.

One additional note: you may hear people saying, “lineal feet” instead of “linear feet.” Though they mean the same thing, the correct term is linear feet.

Area

Sometimes we hear customers mistakenly use the term “board feet” when what they are actually referring to is area. When calculating the amount of materials you need for large surfaces (ex. exterior siding), knowing the area of the space you’ll need to cover is the first step. This is where middle school math comes in handy.

Surface area calculations are simple: Length x Width, which gives you total square feet. Don’t worry about subtracting anything out for windows and doors (better to have a little too much wood than not enough) and always buy an additional small percentage to account for downfall (the occasional warped or discolored board that you don’t want to use).

The final definition of board feet

The true definition of “board feet” is not a calculation of length. Believe it or not, it’s a calculation of volume. The term is most often used by lumber producers who need to determine how many board feet they can obtain from each tree they harvest. Therefore, this is not a term that you will likely ever need to use at the lumber yard.

However, if the term has piqued your curiosity, here’s a quick run-down.

One board foot is measured as 1x12x1 . Notice that this board is a square (1 foot equals 12”).

A 1x6x1 has 0.5 board feet. This board has half (0.5) the volume of the 1x12x1 board.

Sometimes it helps to visualize the “missing” half of the board foot.

A 1x10x1 has 0.833333 board feet (We multiply the 1” thickness by the 10” width then divide by 12 to calculate our board foot factor (BFF), which is the number of board feet per linear foot. So, this 1’ long board has 0.833333 board feet of material.

A 2x6x1 has …one board foot of volume. That’s right, ONE board foot.

Why? Imagine that you started with a 1x12x1, which we know equals one board foot. Then imagine you moved 0.5 board feet from the right side of the board and stacked it on top of the left side of the board to create a 2×6. The volume of material didn’t change.

A 2x8x1 has 1.333333 board feet. Since a 2×6 has one board foot, divide this 8” width by 6 to calculate the board foot factor of 1.333333. A 2x4x1 has 0.6666667 board feet Since a 2×6 has one board foot, divide the 4” width by 6 to calculate the board foot factor of 0.6666667, etc.

To calculate the BFF: (Thickness x Width) /12.  Or, use this handy Board Foot Factor (BFF) table.

Now let’s look at how Board Feet works for more traditional lengths of lumber. 

To calculate total board feet: Board Foot Factor x Length

A 1x12x10 board has 10 total board feet in it: the board foot factor (BFF) of a 1X12 is 1. Multiply 1 by the length of 10, which gives total board feet of 10.

A 1x6x10 board has 5 total board feet in it: the board foot factor (BFF) of a 1×6 is 0.5. Multiply 0.5 by the length of 10 which gives total board feet of 5.

Tip: Both of these previous boards measure 10 Linear Feet (LF) because, remember, LF does not take thickness and width into consideration.

A 2x4x10 board has 6.66667 total board feet in it: the board foot factor (BFF) of a 2×4 is 0.666667. Multiply 0.66667 by the length of 10 which gives total board feet of 6.66667.

A 2x4x14 board has 9.33333 total board feet in it: The board foot factor (BFF) of a 2×4 is 0.66667. Multiply 0.66667 by the length of 14 which gives total board feet of 9.33333, and so on…

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Using the correct terms as you talk about your project helps our lumber specialists make sure you’re buying what you need. So, unless you’re thinking of getting into the logging industry, the measurement terms you’ll need are probably linear feet and square feet, but unlikely board feet. That said, talk to the team at the lumber yard about your projects so they can make sure you’re covered.

Need some assistance estimating the cost of your upcoming lumber project? Our local lumber specialists can help.