Understanding Lumber Measurements — with Board Foot Calculator

Stack of pine boards.

While lumber is commonly sold by the piece in building supply stores, wholesalers and hardwood dealers usually price their stock by the board foot. Ask for a dozen two by fours eight feet long at your local sawmill, and you’ll be told that what you really want is 64 board feet of lumber.

It’s not as confusing as it sounds — as long as you remember that a board foot is a measure of volume equal to a square foot one inch thick. So a 1-inch by 12-inch a foot long and a 2-inch by 6-inch of the same length both equal one board foot. Rough lumber measurements in width and thickness are used when calculating board feet even if the lumber has been planed down.

To calculate the number of board feet, use the following formula:
thickness (inches) x width (inches) x length (feet) ÷ 12 = board feet

Below are some common widths and their equivalent in board feet per foot of length:
• 1” x 4” x 1’ = 0.33 bd. ft.

• 1” x 6” x 1’ = 0.50 bd. ft.

• 1” x 8” x 1’ = 0.67 bd. ft.

• 1” x 10” x 1’ = 0.83 bd. ft.

• 1” x 12” x 1’ = 1.0 bd. ft.

• 2” x 4” x 1’ = 0.67 bd. ft.

• 2” x 6” x 1’ = 1.0 bd. ft.

• 2” x 8” x 1’ = 1.33 bd. ft.

• 2” x 10” x 1’ = 1.67 bd. ft.

• 2” x 12” x 1’ = 2.0 bd. ft.

To find the number of board feet, multiply the number above by the length of the board, then multiply the total by the number of boards needed.

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  1. I need to side a barn which is 4500 square ft.
    I’m using rough cut lumber.
    I would like to use random widths. 8″ ,10″, 12″ widths. All 1″ thickness all 10′ lengths.
    What would be the footage of board feet needed.?

  2. Want to cover a wall 8′ x 12.2′ (with 36″ x 36″ window in the middle of it) with old fence boards 8’x 6″ x 1″.

  3. We just built a house and in efforts to save money we decided to cover the floor of our 1145 sq foot home with cedar fence post cut in rounds 1inch by 4inch and the usable amount is about 5 foot of each post. My question is approximately how many fence posts will I need?

  4. I need to build a wheelchair ramp 26 feet long “L” shaped with a 5′ square to turn the corner. The ramp is 42″ wide. I think I’ll use 5/4 x 6 board running width wise. I need to know how many boards with maybe 1/4″ gap between them. I was looking at 8′ boards. Can you help?


  5. Hello Want to know how many sticks of this dimensions 1.10236″ x 5.90551″ x 7.54593′ makes one BDFT and How many BDFT can be loaded in 1 x 40ft HC Container.
    Thanks and looking forward to your answer.

    • Hi, Terry,
      To calculate the number of board feet, use the following formula (it will require some additional information about the materials you’re working with):
      thickness (inches) x width (inches) x length (feet) ÷ 12 = board feet
      Thanks for reading!

  6. I neede to find the board feet of a circular log /bord 36 diameter , 3 inches thick, ple4ase reply. hat is the formula. thank you’

  7. I am spraying the inside of a metal shipping container with spray insulation and I can’t seem to do the calculations. I need to spray 90′ (long) by 8 ‘ (high.) (or) 720 square feet.

    Can anyone tell me how many board feet that is?

  8. How do i figure out how many board ft are in 4/4 4ft wide 25 layers high 8ft long bundle of ruff cut pilot lumber? Also at 40 cent a board ft what is the math at figuring the total price? Thankyou!

    • Hi, Socrates!
      This calculator helps determine the number of board feet, or bd. ft., needed before you order from the home center.
      Good luck with your project!

  9. I need something built that is 72″ x 35″ x 2″. The guy I got to do it said I needed 75 board feet, but the calculator above says he needs 35 board feet. Is he ripping me off?

    • Hi, Jennifer!
      Without knowing the project’s full details, it’s not possible to determine whether you’re being overcharged.
      We recommend using the calculator below, and asking the contracted worker any questions as they arise.
      Good luck!


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