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Board Foot Calculator

Lumber yards often sell hardwood and rough-sawn timber by the board foot. Enter the thickness, width and length of your boards and how many you need, and get the total board feet and an estimated cost.

Quick answer: A 2 by 6 board that is 8 ft long holds 8 board feet, so ten of them come to 80 board feet.

Your measurements

in
in
ft
qty
$

Total lumber

80board feet

Board feet per piece
8
Cubic feet of lumber
6.67

Use the nominal size the lumber is sold by, such as 2 x 6, not the smaller finished size. One board foot is a piece 1 inch thick, 12 inches wide and 12 inches long.

How to use this calculator

  1. Enter the thickness and the width of one board in inches.
  2. Enter the length of one board in feet.
  3. Enter how many pieces you need.
  4. Add the price per board foot to see the cost per piece and the total.
  5. Use the nominal size that the lumber is sold by, for example 2 by 6.

How the numbers are calculated

One board foot is the volume of a board 1 inch thick, 12 inches wide and 12 inches long, which is 144 cubic inches. The calculator multiplies thickness in inches by width in inches by length in feet and divides by 12.

It then multiplies by the number of pieces for the total. Cubic feet are the total board feet divided by 12, and cost is board feet times the price you entered.

Worked example

A 2 by 6 board that is 8 ft long holds 2 times 6 times 8 divided by 12, which is 8 board feet. Ten of them give 80 board feet, or 6.67 cubic feet. At $3.50 per board foot, one piece costs $28.00 and the total is $280.00.

Tips before you buy

  • Always use the nominal size listed by the seller. A 2 by 4 is priced as 2 by 4 even though it measures less once planed.
  • Buy 10% to 20% more than you need to allow for defects, knots and cuts.
  • Ask whether the price is per board foot or per piece. Comparing the two is the easiest way to check a quote.
  • Rough-sawn lumber loses thickness when you plane it, so order thicker boards than the finished size.
  • Let lumber adjust to your shop for a few days before you cut it, so it does not move after you build.

Frequently asked questions

How do you calculate board feet?

Multiply thickness in inches by width in inches by length in feet, then divide by 12.

How many board feet are in a 2 by 4?

A 2 by 4 that is 8 feet long holds 5.33 board feet, since 2 times 4 times 8 divided by 12 is 5.33.

How many board feet are in a cubic foot?

There are 12 board feet in one cubic foot of lumber.

Do I use actual or nominal size?

Use the nominal size. Lumber is sold by its nominal dimensions, so that is the figure the price is based on.

Quick answers

Related calculators

These results are estimates for planning purposes. Material sizes, densities and local requirements vary, so confirm quantities with your supplier or a qualified contractor before ordering.

Last updated October 11, 2026.