Board Feet — Woodworking Glossary

Board Feet

Board feet (BF) is the standard unit of volume used to price and sell hardwood lumber in North America. One board foot equals 144 cubic inches of wood — equivalently, a piece 1 inch thick, 12 inches wide, and 12 inches long. Softwood dimensional lumber (2×4s, 2×6s) is typically sold by the linear foot, but rough and S2S hardwoods are almost universally priced per board foot, which is why understanding the unit is essential any time you are budgeting a hardwood project.

The Board Foot Formula

BF = (T × W × L) / 144

Where T is thickness in inches, W is width in inches, and L is length in inches. If you prefer to work in feet for the length dimension:

BF = (T × W × L_feet) / 12

The key insight is that the formula captures volume. A board that is thicker, wider, or longer contains more board feet — and costs more — regardless of how many linear feet it spans.

Important: Thickness Is Always Nominal

Hardwood lumber is sold and measured at its nominal (rough) thickness before surfacing. A piece described as 4/4 ("four-quarter") started at 1 inch thick. After surfacing two sides (S2S) it may finish at 13/16" or 7/8", but it is still priced as 4/4 — 1 inch thick for the board foot calculation. Common nominal thickness designations:

Always use the nominal thickness when calculating board feet for purchasing purposes.

Example Calculations

Example 1: An 8-foot board of 4/4 × 6"

BF = (1" × 6" × 96") / 144 = 576 / 144 = 4 BF

At $8.00/BF for hard maple, this board costs $32.00.

Example 2: A 6-foot board of 8/4 × 10"

BF = (2" × 10" × 72") / 144 = 1440 / 144 = 10 BF

At $6.50/BF for white oak, this board costs $65.00.

Example 3: Lumber yard sells a board measured in inches

A board tagged 1" × 7.5" × 84": (1 × 7.5 × 84) / 144 = 4.375 BF. Most yards round to the nearest 1/4 BF.

Common Lumber Dimensions in Board Feet Per Linear Foot

This table shows how many board feet you get per linear foot for common rough hardwood dimensions. Multiply by the board length to get total BF.

Why Board Feet Matter for Budgeting Projects

When you build a cut list without tracking board feet, you are guessing at material cost. Hardwood prices range from $3/BF for common domestic species to $30/BF or more for figured exotics. A dining table in figured walnut might require 40–60 BF of lumber. At $18/BF that is $720–$1,080 in raw material alone — before hardware, finish, and time. Getting the board foot count wrong by 20% is a $150–$200 budgeting error on a single project.

Board footage also determines how many boards to purchase. Lumber is not sold in exact lengths; you buy what the yard has. When you know your cut list requires 28.5 BF of 4/4 cherry, you can select boards at the yard to hit that target, accounting for typical yield losses from defects (knots, checks, sapwood) and from the layout itself.

A common rule of thumb is to add 20–30% to your net board foot requirement as a waste allowance — more for figured or knotty stock, less for clear, wide boards. Net BF is what your parts require; gross BF is what you order.

How Cutly Calculates Board Footage

Cutly tracks board footage automatically for every part in your cut list. As you add parts and assign them to lumber stock, Cutly accumulates the total BF consumed — using nominal thickness for the calculation, consistent with how lumber yards price their material. The project summary shows both the net BF required by your parts and the gross BF you should order, based on your configured waste allowance.

When you use the lumber layout optimizer, Cutly allocates parts across boards and shows the board footage of each board used, the waste per board, and the total material cost based on the species price you enter. This makes it straightforward to compare layouts: a layout that uses 32 BF of walnut versus one that uses 36 BF represents a real cost difference you can see before cutting anything.

Related terms: Kerf, Grain Direction, Linear Foot, Yield, Waste Factor