Board Foot Calculator

Please enter thickness, width, length and pieces greater than 0.
–total board feet
–board feet per piece
–cubic feet
–linear feet

Uses the actual (rough) size you enter. Nominal lumber sizes are smaller than the name suggests.

How to use this calculator

Enter the thickness and width in inches, the length in feet and the number of boards. Add a price per board foot if you want a cost estimate. Press Calculate to see the total board feet.

The formula

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

Example: One board that is 2 in × 6 in × 8 ft is 8 board feet. Ten of them are 80 board feet, which costs $320 at $4 per board foot.

How to use board feet when buying lumber

Board feet measure the volume of wood, not its length. This matters most when buying hardwood, which lumberyards usually price per board foot. The total from this calculator lets you compare prices, plan a project budget and check a yard’s quote.

What the result means in practice

One board foot is a piece 1 inch thick, 12 inches wide and 12 inches long. A board that is twice as thick has twice the board feet, even if its length and width stay the same. That is why thick stock costs much more than thin stock of the same species.

For example, a 1 in by 6 in board that is 8 ft long holds 4 board feet. An 8/4 (2 in thick) walnut board that is 8 in wide and 6 ft long holds 8 board feet. If that walnut costs $12 per board foot, the board costs $96.

Main factors that change the total

  • Thickness: Hardwood is often sold in quarters. 4/4 is 1 inch, 5/4 is 1.25 inches, and 8/4 is 2 inches.
  • Rough vs. surfaced size: Rough lumber is measured before planing. After surfacing, a 4/4 board ends up thinner, but you still pay for the rough size.
  • Random widths and lengths: Hardwood boards often vary in width, so each one is measured and the board feet are added up.

Tips and common mistakes

  • Do not mix units. Thickness and width go in inches, length goes in feet.
  • Buy extra for defects. Knots, checks, splits and sapwood mean you cannot use every inch. Many woodworkers add about 20 to 30 percent to their cut list.
  • Plan your cuts before shopping. Knowing the lengths you need helps you pick boards that waste less.
  • Check moisture content. Wood for indoor furniture should be properly dried.

Planning and cost advice

Start with a cut list of every part in your project. Add up the board feet of each part, then add your waste allowance. This gives you a target to bring to the yard. Ask whether the price is for rough or surfaced lumber, and whether the yard charges extra to plane or rip boards. Prices vary a lot by species and grade, so compare per-board-foot prices rather than per-board prices. Higher grades, such as FAS, give longer clear cuts and less waste. Lower grades cost less but may be fine for small parts.

Frequently asked questions

What is a board foot?
A board foot is a unit of lumber volume equal to a piece 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches.
How do I 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 2×4 that is 8 feet long?
A 2×4 that is 8 feet long is about 5.33 board feet using the nominal size of 2 in by 4 in.
How many board feet are in a cubic foot?
One cubic foot equals 12 board feet.
Do I use nominal or actual size?
Hardwood is usually sold by rough size, so use the size you are charged for. Softwood framing is often priced per piece or per linear foot.
How do I convert linear feet to board feet?
Multiply the thickness in inches by the width in inches, then divide by 12. That gives the board feet in one linear foot. Multiply that by the number of linear feet. For example, a 1 in by 6 in board has 0.5 board feet per linear foot, so 20 linear feet equals 10 board feet.
What does 4/4 or 8/4 lumber mean?
This is the quarter system used for hardwood. The number before the slash is the thickness in quarter inches. 4/4 is 1 inch thick, 6/4 is 1.5 inches, and 8/4 is 2 inches. These are rough thicknesses. After surfacing, a 4/4 board typically ends up about 3/4 to 13/16 inch thick.
How do I calculate board feet for a log?
Logs are estimated with log scale rules, such as Doyle, Scribner or International 1/4-inch. These use the small-end diameter and log length, and each rule gives a different result. The board foot formula on this page measures sawn lumber, not round logs. Ask the sawmill which log rule they use.