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CalcBelt

Board foot calculator

Add up board feet for one board or a whole cut list, using nominal lumberyard sizes or measured sizes, and price it per board foot.

Units
Sizes you're entering
Boards
80 board feet

Board feet are counted on nominal sizes: a 2 × 6 counts as 2 × 6 in even though it measures 1 1/2 × 5 1/2 in dry. Anything under 1 in counts as 1 in.

Lumber

80 board feet

10 pieces · 0.189 m³

Cubic feet
6.6712 board feet make a cubic foot
Cubic meters
0.189
Wood actually there
55 bd ftA 2 × 6 is 1 1/2 × 5 1/2 in once dried and planed

Cost (optional)

per board foot

From your lumberyard. There is no default: species and grade set the price.

How it's calculated
  1. 2 in × 6 in × 8 ft ÷ 12 = 8 board feet × 10 pieces = 80
  2. Total: 80 board feet = 6.67 cu ft (0.189 m³)

Estimates use manufacturer data sheets and industry guides (sources). Check local codes and your supplier's figures before you order.

How to use the board foot calculator

  1. Choose Nominal for lumberyard sizes like 2 × 6, or Actual for rough hardwood and measured boards.
  2. Enter the thickness and width in inches and the length in feet, then the number of pieces.
  3. Click Add another size for each different board on your list.
  4. Read the total board feet, and add your price per board foot to get the cost.

How to calculate board feet

Board feet = thickness (in) × width (in) × length (ft) ÷ 12

The ÷ 12 comes from the definition: a board foot is 12 × 12 × 1 in, or 144 cubic inches, and a foot of length is 12 inches. If you measure the length in inches too, divide by 144 instead.

Example: ten 2 × 6s, 8 ft long. Each is 2 × 6 × 8 ÷ 12 = 8 board feet, so ten are 80 board feet. At $1.50 a board foot, an example price, that’s $120. Dried and planed, those boards actually measure 1 1/2 × 5 1/2 in, which is 55 board feet of wood: the lumberyard still counts 80.

Board feet for common sizes

Board Board feet
1 × 6 × 8 ft 4
1 × 12 × 10 ft 10
2 × 4 × 8 ft 5.33
2 × 6 × 8 ft 8
2 × 8 × 10 ft 13.33
2 × 10 × 12 ft 20
2 × 12 × 16 ft 32
4 × 4 × 8 ft 10.67

Nominal and actual sizes

Softwood lumber is sold by nominal size, and the dried and planed board is smaller. These are the standard dry sizes from the American Softwood Lumber Standard, as listed in the USDA’s Wood Handbook:

Nominal Actual (dry)
1 in thick 3/4 in
5/4 (1 1/4 in) thick 1 in
2 in thick 1 1/2 in
4 in thick 3 1/2 in
4 in wide 3 1/2 in
6 in wide 5 1/2 in
8 in wide 7 1/4 in
10 in wide 9 1/4 in
12 in wide 11 1/4 in

Board feet are still counted on the nominal size. To find the wood actually in a board, switch the calculator to Actual and enter the measured size.

Converting board feet

12 board feet make 1 cubic foot, and 1 board foot is 0.00236 cubic meters. A thousand board feet, written MBF, is about 2.36 m³.

Questions and answers

What is a board foot?

A volume of wood equal to a board 12 in long, 12 in wide and 1 in thick, or 144 cubic inches. It's the USDA Forest Products Laboratory's definition, and 12 board feet make a cubic foot.

How do you calculate board feet?

Multiply the thickness in inches by the width in inches by the length in feet, then divide by 12. A 2 × 6 that's 8 ft long is 2 × 6 × 8 ÷ 12 = 8 board feet.

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

5.33. 2 × 4 × 8 ÷ 12 = 5.33 board feet, counted on the nominal size. A 2 × 10 × 12 is 20 board feet and a 4 × 4 × 8 is 10.67.

Do you use nominal or actual size for board feet?

Nominal. The Wood Handbook says the count for lumber 1 in or thicker uses the nominal thickness and width and the actual length, and anything under 1 in nominal counts as 1 in. A 2 × 6 counts as 2 × 6 even though it measures 1 1/2 × 5 1/2 in dry. Switch to Actual to work out the wood that is really there.

What does 4/4 or 8/4 mean?

Thickness in quarters of an inch, as the Wood Handbook writes it for hardwood: 4/4 is 1 in, 5/4 is 1 1/4 in and 8/4 is 2 in, rough. Under the handbook's standard hardwood sizes, 1 in rough lumber planed on both sides comes out 13/16 in thick.

How much does lumber cost per board foot?

It depends on the species, the grade and where you buy, so the calculator has no default price. Type your lumberyard's price per board foot to get the total.

How many board feet are in a 1 × 12 × 12?

12. A 1 × 12 that is 12 ft long is 1 × 12 × 12 ÷ 12 = 12 board feet.

How do I convert board feet to square feet?

For 1 in lumber, one board foot covers one square foot of face. For other thicknesses, divide the board feet by the thickness in inches: 24 board feet of 2 in lumber covers 12 sq ft. Board feet use nominal sizes, so the real face is a little smaller.

Sources

Figures checked October 2026.