Lumber Tally field notes

Board Feet vs. Linear Feet

Board feet measures volume; linear feet measures length. Convert between them only when you know the thickness and width.

Linear feet and board feet answer two different questions. Linear feet asks "how long is this board?" Board feet asks "how much wood is in this board?" A board's length alone does not tell you its volume. If a supplier quotes a price per linear foot, check which thickness and width that price covers.

Why length alone is not enough

Two boards can both be 8 feet long and still hold very different amounts of wood:

Both boards are 8 linear feet. One holds three times as much wood as the other. To compare a linear-foot price with a board-foot price, you need the cross-section used in the quote. A wider board may have a different price per linear foot even when the price per board foot is the same.

When each measure fits

• Linear feet — trim, molding, baseboard, and any run of lumber sold at one fixed cross-section, where you only need to know how far it reaches.
• Board feet — rough-sawn stock, slabs, and any hardwood or mixed-size lot, where thickness and width vary board to board and the actual volume of wood is what you are paying for.

Converting between them

You cannot go from linear feet to board feet without also knowing thickness and width:

board feet = linear feet × (thickness in × width in) ÷ 12

For an illustrative board measuring a full 2 inches thick and 6 inches wide, priced at $3/linear ft, one linear foot is 2 × 6 ÷ 12 = 1 board foot, so $3/linear ft is also $3/board foot for that specific size only. Change the width or thickness and the relationship changes with it — which is why a board-foot tally, not a running length, is what carries across a mixed order. See how to calculate board feet for the formula, or go straight to the calculator to tally a mixed list.