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Board Foot Calculator

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List your boards by thickness, width, length and quantity to get total board feet and the lumber cost at your yard’s price per board foot.

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Total lumber

Enter thickness, width, length and quantity.

How to use the board foot calculator

  1. Enter each size of board: thickness and width in inches, length in feet, and how many you need.
  2. Use nominal sizes for softwood framing lumber (2 × 6, not 1½ × 5½), since that’s how board feet are figured and priced.
  3. For rough hardwood, enter the thickness in inches: 4/4 is 1 in, 5/4 is 1.25 in, 8/4 is 2 in.
  4. Add your yard’s price per board foot to total the order.

Board foot formula

Board feet = thickness (in) × width (in) × length (ft) ÷ 12
Board feet = thickness (in) × width (in) × length (in) ÷ 144
Cost = board feet × price per board foot

A board foot is 144 cubic inches, “a board one inch thick, 12 inches wide, and 12 inches long,” as the Virginia Department of Forestry
defines it. The American Softwood Lumber Standard (PS 20) says the number of board feet is found from the nominal thickness and width
and the length, which is why a 2 × 4 counts as 2 × 4 even though it’s dressed to 1½ × 3½ in.

Worked example: ten 2 × 6 boards, 12 ft long

  1. One board: 2 × 6 × 12 ÷ 12 = 12 board feet.
  2. Ten boards: 12 × 10 = 120 board feet.

A hardwood board 1 in (4/4) thick, 8 in wide and 8 ft long is 5.33 board feet. At an example price of $6.00 per board foot, it costs $32.00.

Board feet for common sizes

Nominal size Length Board feet Actual size (dry)
2 × 4 8 ft 5.33 1.5 × 3.5 in
2 × 6 8 ft 8 1.5 × 5.5 in
2 × 8 10 ft 13.33 1.5 × 7.25 in
2 × 10 12 ft 20 1.5 × 9.25 in
2 × 12 16 ft 32 1.5 × 11.25 in
4 × 4 8 ft 10.67 3.5 × 3.5 in
1 × 6 8 ft 4 0.75 × 5.5 in

Actual sizes are the minimum dry dressed sizes in PS 20 Table 3.

Tips for buying lumber

  • Check how the yard prices. Framing lumber is often sold by the piece or the linear foot; hardwood is usually sold by the board foot. Convert to compare.
  • Buy extra for defects. Knots, checks and warp mean some of every order ends up as offcuts.
  • Rough vs. surfaced hardwood. Rough boards are measured before planing, so a 4/4 board ends up thinner than 1 in once surfaced.
  • Pricing by length? The linear feet calculator totals boards by length instead.

Questions

How many board feet are in a 2 × 4 × 8?

2 × 4 × 8 ÷ 12 = 5.33 board feet.

Do I use actual or nominal size?

Nominal for softwood lumber, per the American Softwood Lumber Standard. For rough hardwood, use the thickness in quarters (4/4 = 1 in) and the measured width.

What’s the difference between a board foot and a linear foot?

A board foot is a volume (144 in³); a linear foot is a length. A 1 × 12 has one board foot per linear foot, while a 2 × 4 has two thirds of a board foot per linear foot.

How many board feet are in a cubic foot?

12. A cubic foot is 1,728 in³, and 1,728 ÷ 144 = 12.

Sources

  1. Glossary: Board foot, Virginia Department of Forestry.
    Used for: A board foot is 144 cubic inches (1 in × 12 in × 12 in).
  2. Voluntary Product Standard PS 20-20: American Softwood Lumber Standard, NIST / American Lumber Standard Committee.
    Used for: Board feet are figured on nominal sizes (section 2.2); nominal vs. dry dressed sizes (a 2 × 4 is 1 1/2 × 3 1/2 in).

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