What is a board foot?

A board foot is a unit of lumber volume equal to a board 1 inch thick, 12 inches wide, and 12 inches long — that is, 144 cubic inches. Hardwood is almost always sold by the board foot rather than by length.

What is the board foot formula?

Board feet equal thickness in inches times width in inches times length in feet, divided by 12. If your length is in inches instead, multiply by length and divide by 144. The result is the same volume measured in board feet.

Should I use nominal or actual thickness?

Lumber is priced and tallied at its rough nominal thickness before surfacing, so use the nominal figure (for example 4/4 hardwood counts as 1 inch even though it dresses to about 13/16 inch). Width and length use rough dimensions too.

How do I convert board feet to cubic feet?

One board foot is 144 cubic inches and one cubic foot is 1728 cubic inches, so one cubic foot equals exactly 12 board feet. Divide board feet by 12 to get cubic feet, and multiply cubic feet by about 0.0283 to get cubic metres.

Does the calculator handle a mixed cut list?

Yes. Add as many different board sizes and quantities as you need and the running total tallies every piece. This is the same way a lumber yard tallies a mixed order before pricing it per board foot.

What is the Board Feet Calculator?

Computes board feet using BF = (thickness_in × width_in × length_ft) / 12 for single boards and lumber lists. Add multiple pieces for a running total, and convert between board feet, cubic feet, and cubic metres for any lumber order. It runs free in your browser on Gera Tools, with nothing uploaded.

Board Feet Calculator

Name: Board Feet Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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A board foot is the standard volume unit for selling rough lumber, especially hardwood. This calculator applies the board-foot formula to a single board or a full mixed cut list, then expresses the total in board feet, cubic feet, and cubic metres so you can place or price an order with confidence.

Understanding the unit matters before you order: a board foot is not a length, it is a volume. Two boards that look very different — a wide short piece and a narrow long piece — can contain exactly the same board footage. Hardwood dealers price by board foot precisely because it captures volume regardless of shape.

How it works

Every piece is reduced to a volume in board feet, where one board foot is a board 1 inch thick by 12 inches wide by 12 inches long:

board feet (one piece)  = (thickness_in × width_in × length_ft) / 12
board feet (a quantity) = board feet × pieces

The grand total is then converted to other volume units using fixed ratios:

cubic feet   = total board feet / 12
cubic metres = cubic feet × 0.0283168

Because one cubic foot is exactly 12 board feet, those conversions are exact — there is no rounding hidden inside them.

Worked example: a hardwood project

Suppose you need the following lumber for a dining table:

2 pieces of 4/4 walnut, 10 inches wide, 6 feet long (tabletop slabs)
4 pieces of 8/4 walnut, 3 inches wide, 30 inches long (legs, converted to 2.5 ft)

Tabletop: (1 × 10 × 6) / 12 = 5 BF each × 2 = 10 BF Legs: (2 × 3 × 2.5) / 12 = 1.25 BF each × 4 = 5 BF Total: 15 board feet — add 10–15% for waste, so order around 17 BF.

Common mistakes and tips

Use nominal thickness, not dressed thickness

Lumber is tallied at its rough nominal size. 4/4 hardwood counts as 1 inch for pricing even though it finishes to about 13/16 of an inch after planing. 8/4 counts as 2 inches. If you use the dressed thickness, you will undercount the board footage you are actually paying for.

Add a waste allowance

Raw board footage does not account for defects, wane, or saw kerfs. Most woodworkers add 10–20% for typical hardwoods and more for highly figured stock where you may reject sections.

Softwood is different

Softwood dimensional lumber (2×4, 2×6, etc.) is sold by the linear foot at lumber yards, not by the board foot. Board-foot tallies are most relevant when buying rough hardwood from a sawmill or specialty dealer.

Length in inches

If you know your length in inches rather than feet, divide by 12 before entering, or use the inches field the tool provides — it handles the conversion internally.