How to Calculate MBF of Lumber

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The board-foot (BF) is a unit of volume that specifically measures lumber. It is an estimate of the volume of raw lumber and is primarily used in the United States and Canada, although the term "super foot" (superficial foot) is used in Australia and New Zealand for the same unit of measure. The letter "M" stands for 1,000 in the lumber industry, so "MBF" is the abbreviation for 1,000 board feet. The definition of BF refers to a base volume that must be adjusted according to the specific type of lumber that is being measured.


Step 1

Define the base volume for a BF. This is given as the volume equal to a board one foot long, one foot wide and one inch thick. This volume of a BF is therefore 12 x 12 x 1 = 144 cubic inches.

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Step 2

Convert a cubic inch to cubic meters. There are 2.54 centimeters to the inch so there are 2.54/100 = 0.0254 meters to the inch. Therefore, there are (0.0254)^3 = 0.0000164 cubic meters in a cubic inch.


Step 3

Convert the base volume for a BF to cubic meters (m^3), the standard units of volume. There are 144 cubic inches in a BF and 0.0000164 cubic meters in a cubic inch, so there are 144 x 0.0000164 = 0.00236 cubic meters in a BF.

Step 4

Use the BF as an approximate unit of measure for lumber that has not been dried and planed. The dimensions of raw lumber can't be calculated easily because it does not have a consistent shape.


Step 5

Convert the BF measure for raw lumber to the actual volume planed lumber. Reduce each linear dimension of raw softwood lumber by one-quarter inch for measures less than 2 inches, one-half inch for measures less than 8 inches and three-quarter inch for measures greater than 8 inches. Multiply the resulting measures together to obtain the volume of the planed lumber.



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