Board Foot Calculator

What’s a Board Foot?

Used throughout North America, a board foot is a unit of measurement for the volume of rough lumber. Since wood comes in all lengths, widths, & thicknesses, board feet can easily quantify these variables into a single number. Thus, lumber yards tend to leverage this unit of measurement in their pricing models. The equation for board foot is a variation of your standard Length x Width x Height formula with a twist:

 
^{( Length _Feet x Thickness _Inches x Width _Inches )} ⁄ ₁₂

 
While there are other ways to calculate board feet, this is generally the most useful formula. That is, inches are normally used to represent the width and the thickness of lumber while the length is best measured in feet. In any case, the final number should be interpreted as just board feet (BDFT or BF). If your final number has a decimal, you should leave it rather than attempting to convert the value to inches.

Measuring Board Feet

Unlike dimensional lumber, rough lumber should be measured by the actual dimensions. For instance, a 4″ wide board is actually 4″ wide rather than only being 3.5″ wide. In fact, the width of rough lumber should never be rounded up as one might assume. Another item to keep in mind is that the width should be based on the narrowest part of the board. While this may come as a pleasant surprise to a novice wood worker, you won’t end up with any more wood after you square the edges.

While the width and length measurements are straight forward, the thickness is a different story. Most lumber yards will represent the thickness in ¹/₄ inch increments. For instance, 1″ is written as ⁴/₄ inch, 1.5″ is ⁶/₄ inches, 2″ is ⁸/₄ inches, 3″ is ¹²/₄ inches, and so on. The only exception to the rule is that 0.5″ is often represented as ¹/₂ inch.

Rough Lumber Buying Guide

Before you buy your rough lumber, you’re going to want to read this. Depending on the lumber yard, some might create a contractor’s edge on the side of each board. For those of you without a wood jointer, this is good news! That is, the lumber yard (or manufacture) is providing you with at least one straight edge to speed up the squaring-up process. They normally differentiate the straight edge from the live edge by marking one of the live edge’s corners.

When shopping for rough lumber, you may notice that the prices aren’t always posted. The reason for this is that the prices are frequently changing based on the supply and demand. If the growing conditions for a given wood species are poor, the wood harvests will not only yield less, but the lumber produced will be of lower quality. As a result, we always recommend asking your local lumber store which species are priced aggressively verses which ones should be avoided?

Stocking plays a big role on the quality of wood that you can find. When a new shipment arrives, the shoppers first to he party get the cream of the crop. Thus, anyone looking for a specific species should call their local lumber yard to determine the best day to shop. Even when the supply for a given wood species is healthy, it’s always worth aiming to shop right after the restock date.