Board Feet for Dummies

Definition of a board foot

The tiny bios written by the "contributors" at eHow.com seem so amusing sometimes: these folks come off as renaissance men and women with their wide-ranging interests and education. Take, for example, today's DotD nominee, Matthew Anderson (aka Matthew Abdallah): he claims a degree in chemical engineering, a decade of "publishing," and training in music. What he doesn't have, as will be seen in a moment, is even the most basic knowledge of carpentry; as is clearly displayed by his post at Hunker.com. "How to Convert Square Foot to Board Foot."

The illiteracy of the title isn't Anderson's fault – that's on eHow.com, which refused to change wording of the "titles" they scraped from internet searches. The remainder of the post? that's all on Matthew! So, readers, the answer is quite simple: a board foot is a square foot of lumber one inch thick. In other words, all you have to do to convert square feet to board feet is divide the area of lumber in square feet by the thickness of the lumber in inches. Simple, right? Well, Anderson says it's "moderately easy"... but, then, he doesn't know how to do it. Here's what Matt says to do:

1. Divide the thickness of board by 12 to convert it from inches to feet.
2. Multiply the surface area in square feet by the board thickness in feet. This will give the quantity of board feet needed to cover that area.

		Really? Did he just say that? Yes, he did! So if you wanted to order lumber to, say, put wood siding on a house, you'd do some measurements. Let's pretend that the wall is 20 feet long and 10 feet high and you intend to put 1-inch boards on it. If you use Anderson's instructions ( l * w * t/12 ), you'll order 10 * 20 * (1 / 12) = 16.7 board ft which is very wrong! On the other hand, if you use the correct formula ( l * w * t ), you'll order 10 * 20 * 1 = 200 board ft

In reality, of course, woodworkers know that you rarely see board feet used in that way, which is where Anderson got sideways with the facts. You see, the board foot is most often used to measure the volume of single boards, especially hardwoods: they're typically priced by the board foot. So it's common to see the formula expressed as

(width in inches / 12) * length in feet * thickness in inches. 

For instance, a chunk of walnut 8 inches wide, 5 feet long and 3 inches thick contains 10 board feet of lumber

(8 / 12) * 5 * 3 = 10 board ft

Matthew didn't know that, and neither did eHow's content editor, yet both of them signed off on this rubbish. As a consequence, this misinformation has been sitting at or near the top of the search results for the topic since 2009. And you wondered why we award a new Dumbass of the Day every day? There's your answer...

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