WoodCalc Pro

Board Foot Calculator

List every board in your order. Thickness takes quarters or fractions (1 1/4), length in feet or inches. The total updates as you type, with waste and cost.

Your boards

16 bf
26.67 bf

Total board feet

42.67bf

With 15% waste
49.1 bf
Cost (with waste)
$318.93
Pieces
6
Linear feet
52
Cubic feet
3.56
Cubic meters
0.101

Formula per board: qty × thickness × width × length(in) ÷ 144.

Why a 2×6 and a 1×12 cost the same per foot

A board foot is a fixed block of wood, 144 cubic inches. Change the thickness or width and see how long the board has to be to hold exactly one board foot.

1" × 12" × 12" = 144 in³ = 1 board foot

So a 1×12 needs 12" of length per board foot, a 2×6 also 12", and a 1×4 needs 36". That is why dealers can price walnut, oak and maple in one unit regardless of the board's shape, and why a thick slab costs more per foot of length than a thin board of the same width.

The board foot formula

Board feet = thickness (in) × width (in) × length (in) ÷ 144, or with length in feet, T × W × L(ft) ÷ 12. Measure rough lumber at its thickest honest dimension: most dealers round width down to the nearest inch (or half inch) and use the rough quarter thickness.

Worked examples

  • One 4/4 walnut board, 7" wide, 8 ft long: 1 × 7 × 8 ÷ 12 = 4.67 bf.
  • Three 8/4 maple boards, 6" × 10 ft: 3 × 2 × 6 × 10 ÷ 12 = 30 bf.
  • A 12/4 slab, 14" × 72": 3 × 14 × 72 ÷ 144 = 21 bf.

Board feet per piece for common lumber

Nominal sizeActual (surfaced)8 ft10 ft12 ft16 ft
1×43/4 × 3 1/2"2.673.3345.33
1×63/4 × 5 1/2"4568
1×83/4 × 7 1/4"5.336.67810.67
1×123/4 × 11 1/4"8101216
2×41 1/2 × 3 1/2"5.336.67810.67
2×61 1/2 × 5 1/2"8101216
2×81 1/2 × 7 1/4"10.6713.331621.33
2×101 1/2 × 9 1/4"13.3316.672026.67
2×121 1/2 × 11 1/4"16202432
4×43 1/2 × 3 1/2"10.6713.331621.33
6×65 1/2 × 5 1/2"24303648

Ask the shop

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Questions people ask

What is a board foot?
A board foot is a volume of wood: 144 cubic inches, the same as a board 1 inch thick, 12 inches wide and 12 inches long. Hardwood dealers in the US sell rough lumber by the board foot, so a 2-inch-thick board half as wide holds the same board footage.
How do you calculate board feet?
Multiply thickness (in) × width (in) × length (in) and divide by 144. If you measure length in feet, divide by 12 instead: thickness × width × length in feet ÷ 12. A 1 × 6 × 8 ft board is 1 × 6 × 8 ÷ 12 = 4 board feet.
Do I use nominal or actual size?
For rough hardwood sold by the board foot, use the rough (nominal) thickness: 4/4 counts as 1", 8/4 as 2", even though it will plane thinner. Dimensional softwood (2×4, 2×6) is normally priced per piece or per linear foot, but lumberyards that quote board feet also use the nominal size, so a 2×6 is figured as 2 × 6.
What does 4/4, 5/4 and 8/4 mean?
It is the quarter system for hardwood thickness in quarters of an inch: 4/4 ("four quarter") is 1", 5/4 is 1¼", 6/4 is 1½", 8/4 is 2", 12/4 is 3". It is the rough-sawn thickness; surfaced 4/4 stock usually ends up about 13/16".
How much waste should I add?
For rough hardwood, woodworkers commonly add 20–30% for defects, sapwood, end checks and yield loss when cutting parts. Clear, straight stock for simple cuts can get by with 10–15%. Figured or knotty boards can need 40% or more.
How many board feet are in a 2×4×8?
Using nominal size: 2 × 4 × 8 ÷ 12 = 5.33 board feet. A 2×6×8 is 8 bf, a 2×10×12 is 20 bf.

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