Board foot

From Wikipedia, the free encyclopedia

The board-foot is a specialized unit of volume for measuring lumber in the United States and Canada. It is the volume of a one foot length of a board one foot wide and one inch of nominal thickness.

Board-foot is abbreviated FBM (for "foot, board measure"). The unit MFBM represents a thousand board-feet.

In Australia and New Zealand the term super foot or superficial foot is used to mean the same.[1]

One board-foot equals:

1 ft × 1 ft × 1 in
12 in × 12 in × 1 in
144 in³
1⁄12 ft³
2.360 liters
0.002360 cubic meters or steres

Board-feet are used for rough lumber (before drying and planing) with no adjustments.

For planed lumber, board-feet refer to the nominal thickness and width of lumber, calculated in principle on its size before drying and planing. Actual length is used.

See dimensional lumber for a full discussion of the relationship of actual and nominal dimensions. Briefly, for softwoods, to convert nominal to actual, subtract ¼ inch for dimensions under 2 inches; subtract ½ inch for dimensions under 8 inches; and subtract ¾ inch for larger measurements. The system is more complicated for hardwoods.