Board Foot Calculator

US & Canada

Enter the board size and how many you have to get board feet, volume in both systems, and the cost at your yard's price.

Your lumber

1. Board size

in
in
ft
boards

Nominal sizes (2 x 6) give the nominal volume; actual sizes (1 1/2 x 5 1/2) give the true volume. Use whichever your yard prices on.

2. Price (optional)

$ / bd ft

Leave at 0 to skip the cost. Use your yard's price.

Result

0

Breakdown

Board feet = thickness (in) × width (in) × length (ft) ÷ 12, from the University of Wisconsin-Madison. 1 board foot = 144 cubic inches = 2.36 litres (calculated).

How board feet are worked out

  • Board feet = thickness (in) × width (in) × length (ft) ÷ 12
  • Total = board feet per piece × number of pieces
  • Cubic feet = board feet ÷ 12; cubic metres = board feet × 0.00235974 (calculated from 144 cubic inches)

The formula and the 144 cubic inch definition come from the University of Wisconsin-Madison and the Virginia Department of Forestry. In metric mode, enter millimetres and metres; they are converted back to inches and feet before the formula runs, so the answer is the same.

Nominal or actual size

Planed lumber is smaller than its name. UW Forestry Facts No. 42 puts it this way: a board-foot figure from nominal size "results in the nominal volume, not the true volume". Its example: a 10 ft 2 × 6 is 10 board feet nominal, or 6.875 board feet at its actual 1 1/2 × 5 1/2 in. The USDA Wood Handbook adds that length is recorded in actual dimensions while width and thickness are traditionally nominal, so check how your seller counts before you compare prices.

Board feet per piece, nominal sizes

Calculated with the formula above, on nominal size.

Board feet per piece by nominal size and length
Size Per linear ft 8 ft10 ft12 ft16 ft
1 × 4 0.333 2.673.3345.33
1 × 6 0.5 4568
1 × 8 0.667 5.336.67810.67
1 × 12 1 8101216
2 × 4 0.667 5.336.67810.67
2 × 6 1 8101216
2 × 8 1.333 10.6713.331621.33
2 × 10 1.667 13.3316.672026.67
2 × 12 2 16202432
4 × 4 1.333 10.6713.331621.33
6 × 6 3 24303648

Sources

Metric equivalents (litres and cubic metres per board foot) are calculated from the inch definition.

Common questions

How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 10 ft 2 × 6 is 2 × 6 × 10 ÷ 12 = 10 board feet, the University of Wisconsin-Madison's own example.
How many cubic inches are in a board foot?
144. One board foot is a piece 12 in wide, 12 in long and 1 in thick. That is 2.36 litres or 0.00236 m³ (calculated), and 12 board feet make one cubic foot.
Do I use nominal or actual size?
Whichever your seller prices on. Nominal sizes give the nominal volume. Using the actual size of a planed 2 × 6 (1 1/2 × 5 1/2 in), a 10 ft board is 6.875 board feet instead of 10, as UW Forestry Facts No. 42 works out.
How many board feet are in ten 8 ft 2 × 4s?
Each is 2 × 4 × 8 ÷ 12 = 5.33 board feet on nominal size, so ten are 53.3 board feet.
How many board feet in twenty 1 × 6 boards 8 ft long?
4 board feet each, so 80 board feet in all (0.189 m³).
What is fbm?
Foot board measure, the Canadian name for the same unit. Nova Scotia's forestry registry defines fbm as "a piece of lumber one foot long, one foot wide and one inch thick or an equivalent volume of lumber".
Why do Canadian code tables show 38 × 89 for a 2 × 4?
NBC 2020 Article 9.3.2.6 says lumber dimensions in Part 9 are actual dimensions, determined under CSA O141. The trade name stays 2 × 4; the code prints the planed size in millimetres.