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A simple way to Calculate Board Feet

October 9, 2018Olen Murriel

While it could be easy to identify a softwood from a hardwood in a bunch of trees, the same isn’t always true once they are cut, dried and stacked in the lumberyard. Hardwoods are typically deciduous trees which lose its leaves annually, they tend to have a slower growth rate and usually very dense. Softwoods, on the other hand, comes from conifer species which remains evergreen throughout the year. Due to their varying structural composition, densities, strength, heat resistance and applications; the prices of the two types of timber differ.

When it comes to the method of calculating the cost of each piece, they’re certain aspects usually taken into consideration. Softwoods and hardwoods are sold separately with varying valuation techniques. Softwoods are dimensional lumber- this means that the cost is directly proportional to the sizes based on raw figures. Softwoods are more often than not, cut into uniform sizes (length X width) and sold at the same price.

Hardwoods are however sold by the board foot. This is done by calculating the cubic size of the board where one board foot is equivalent to 12 X 12 X 1 inches or one-twelfth of one cubic foot. To fully understand these dimensional figures, it’s important to understand the thickness of hardwoods listed below. Board thickness is usually given in fourths.

Typically, board thicknesses will be listed in fourths

  • 3/4 = 0.75 inch
  • 4/4 = 1 inch
  • 5/4 =1 25 inches
  • 6/4 = 1.5 inches
  • 7/4 = 1.75 in
  • 8/4 = 2.0 inches

The formula for calculating the board feet is given by ( length X width X thickness)/ 144- with all dimensions given in inches.

Example

A 6/4 board measuring 8-inches wide and 6-feet long. Here, the length is given in feet and hence it’s necessary to change it to inches for precise and easy calculation. One foot is 12 inches, so the length is equivalent to 72 inches. On calculating, the cubic feet becomes; (72 X 8 X 1 50) = 6.

Another factor to consider is the hardwood species in which the timber was cut. Different hardwood species have a varying cost per board-foot. Once you know the cost per board foot of a given hardwood species and you know the board-feet measurement; then you can determine the price of a given board.

Example

If the board in the example above is mahogany and the lumberyard charges $20 per board-foot of mahogany; then the net cost of the board would be given by, ( $20 X 6 BF)= $120.

The price per board of a given wood species could be subject to some truncation or rounding off to the nearest whole number If, for example; a board measures 5.69 BF (BF=board feet), certain lumberyards will truncate this figure to 5 BF, however, in most cases; the measurements would be rounded to 6 BF. Such adjustments may seem insignificant, but once the final calculations are liquidated, it may end up costing you a lot.

 

Other Factors to consider

If you can’t do some precise approximation with the junky decimal numbers, it’s better to reach out for your phone and do some quick math. If you’re not satisfied with the rounding of numbers, you can bargain for something friendly to your pocket.

Unlike dimensional softwood timber, hardwood timber could have a wide variation in terms of shape, size and even the overall appearance. Since hardwoods are priced per board feet, it possible to find up to 8 different combinations of dimensions that satisfy one cubic foot. For example; a board of 28 BF can have these dimensions: (7 X 4 X 1), (4 X 7X 1) or (1 X 7X 4) and so on. It’s therefore important to find the right measurements that will meet your needs.

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