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Board Foot Calculator

Calculate board feet of lumber from thickness, width, length and number of boards, for planning and buying.

What this tool does

Calculate board feet of lumber from thickness, width, length and number of boards, for planning and buying. You fill in these fields: Thickness, Width, Length, and Number of boards. It shows total board feet and board feet per board.

Inputs

  • Thickness (in): A number. Must be greater than 0. Board thickness in inches.
  • Width (in): A number. Must be greater than 0. Board width in inches.
  • Length (ft): A number. Must be greater than 0. Board length in feet. For a part foot, use decimals: 6 inches is 0.5 feet.
  • Number of boards: A whole number. Must be at least 1. Starts at 1. How many boards of this size you need.

How to use

  1. Enter the thickness in in.
  2. Enter the width in in.
  3. Enter the length in ft.
  4. Enter the number of boards.
  5. Read the result: total board feet and board feet per board. It appears once every required field has a valid value.

Worked examples

Example 1. Inputs:

  • Thickness: 1 in
  • Width: 12 in
  • Length: 8 ft
  • Number of boards: 1

Results:

  • Total board feet: 8.00
  • Board feet per board: 8.00

How this is worked out: Board feet = thickness (in) x width (in) x length (ft) / 12 = 1 x 12 x 8 / 12 = 96 / 12 = 8. Check: length is 96 in, so 1 x 12 x 96 / 144 = 1152 / 144 = 8.

Example 2. Inputs:

  • Thickness: 2 in
  • Width: 4 in
  • Length: 8 ft
  • Number of boards: 10

Results:

  • Total board feet: 53.33
  • Board feet per board: 5.33

How this is worked out: One board: 2 x 4 x 8 / 12 = 64 / 12 = 5.333333. Ten boards: 5.333333 x 10 = 53.333333.

Example 3. Inputs:

  • Thickness: 0.75 in
  • Width: 5.5 in
  • Length: 2.5 ft
  • Number of boards: 1

Results:

  • Total board feet: 0.86
  • Board feet per board: 0.86

How this is worked out: Length 2.5 ft = 30 in. 0.75 x 5.5 x 30 = 123.75 cubic inches, and 123.75 / 144 = 0.859375 board feet.

Limitations

  • Gives board feet only. It does not give prices, cubic volume or the number of boards to buy.
  • Does not add an allowance for cuts, waste or defects.
  • Thickness and width are in inches. Length is in feet.

FAQs

Q: What is a board foot?
A: A board foot is a piece of wood one inch thick, one foot wide and one foot long. That is 144 cubic inches.
Q: Do I enter the size the lumber is sold as?
A: Enter whichever size the price is quoted in, nominal or actual. The tool uses the numbers you type as they are.
Q: Why is the length in feet and the width in inches?
A: Thickness and width are entered in inches, and length in feet, which is how board feet are defined. To use inches for length, divide by 12 first.
Q: Does the result include waste from cutting?
A: No. The result is the board feet of the boards you enter. Add your own allowance for cuts and waste.

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