Board Foot Calculator

One unit, three ways to write it

The definition is the whole tool: A board foot contains 144 cubic inches of sawed lumber or the equivalent of a board 1 inch thick, 12 inches wide and 1 foot long (University of Missouri Extension, G5050). Everything else is arithmetic on it: T″ × W″ × L″ / 144, the same sum as T″ × W″ × L′ / 12, and the same again as thickness × the square feet of face. 1728 / 144 = 12 board feet per cubic foot.

Four sizes go on one order, each with its own takeoff line, and the plate gives back what a board-feet figure hides: pieces, lineal feet, volume, and the piece redrawn. Of the pages we could read, none drew the piece typed in, converted lineal feet or took an allowance.

Nominal or dressed: the sheet asks first

Lumber is billed on the size you are quoted, so that is what the sheet multiplies. A dressed board is smaller, and the softwood standard PS 20-20 gives the minimum dressed dry sizes — nominal 2 in thick is 1-1/2 in, nominal 4 in wide is 3-1/2 in (NIST, Table 3). Tick the option and the section drawing adds the dressed rectangle inside the nominal one: a 2 x 4 x 8 holds 0.2917 cubic feet of wood, 65.6 % of the 0.4444 you pay for.

Nothing from that table is applied until you tick it: 1-1/4 x 7 is both a nominal board of the standard and a rough five-quarter hardwood size, and only you know which is on the truck. A filled line with no nominal row suppresses the dressed total rather than showing part of it.

Price per board foot, and per 1,000

Type a price per board foot and the cost of the rounded order prints beside that price multiplied by 1,000 — the unit sellers write MBF. The three sizes above at 10 % and $3.5 per board foot: order 138 board feet, $483, $3,500 per 1,000. The order is rounded up to the next whole board foot; your supplier may bill fractions.

What this sheet leaves to your supplier

No weight and no species: ask your supplier for the weight per board foot of what you are buying. The allowance starts at zero, so the sheet orders what it measured until you type your own percentage. Quarters are read literally — 5/4 is five quarter-inches, 1.25 in, how hardwood is quoted before dressing — worth confirming with the yard.

Line    BF  =  T" x W" x L" / 144  =  T" x W" x L' / 12   x pieces
Total   BF  =  sum of the filled lines
Order   BF  =  ceil( total x ( 1 + allowance ) )
Volume cuft =  total BF / 12      Cost = order BF x price

Frequently asked

How do I calculate a board foot?

Thickness in inches x width in inches x length in feet / 12, times the pieces. Dividing by 12 rather than 144 is the same sum with the length already in feet.

How many board feet is a 2x4x8?

5.33: 2 x 4 x 8 / 12. Ten of them is 53.33 board feet, 54 once rounded up, over 80 lineal feet.

How many board feet are in a 1x12x12?

12 exactly — 1 x 12 x 12 / 12 — and 1 cubic foot, because a 1 in x 12 in board one foot long is the unit.

How many board feet is a 2x4x10?

6.6667, printed as 6.67 and ordered as 7.

What does 20 board feet mean?

20 x 144 = 2,880 cubic inches of sawed lumber, or 1.67 cubic feet — a volume, not a length or an area. One 1 x 12 x 20 is exactly that much.

How do I calculate how much lumber I need?

Type each size on its own line with its piece count, then your own allowance: the three sizes above total 125.33 board feet, 138 at 10 %.

How to calculate sq ft of wood?

Square feet measures the face only: width in inches x length in feet / 12. Board feet multiplies that face by the thickness in inches, so the two agree only on lumber 1 inch thick. A 1 x 12 x 12 is 12 sq ft of face and 12 board feet; a 2 x 4 x 8 is 2.67 sq ft of face and 5.33 board feet. This sheet counts board feet.

Limits of this sheet

S-201 measures sawn lumber. It does not grade, estimate weight or scale a log: Doyle and Scribner measure logs in a different unit and are out of scope. Confirm sizes and availability with your supplier.

Sheet S-201 prepared by TakeoffMetric Editorial; no author, credential or field measurement is claimed.