BOARD FEET CALCULATOR
Calculate board feet for lumber purchases. Get accurate measurements for pricing and ordering.
What is a Board Foot?
A board foot is the standard unit of measurement for lumber in North America. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide, and 12 inches long (or 144 cubic inches).
The Formula
Board Feet = (Thickness × Width × Length) ÷ 144
Where thickness and width are in inches, and length is in inches. If your length is in feet, multiply by 12 first (or use our calculator which handles this automatically).
Nominal vs Actual Sizes
When buying dimensional lumber (like 2×4s), remember that the stated size is the nominal size, not the actual size. A 2×4 actually measures 1.5" × 3.5". However, when purchasing rough hardwood lumber, you typically buy by actual thickness (often stated in "quarters" like 4/4 for 1", 8/4 for 2", etc.).
Examples
- A 1" × 12" × 12' board = 12 board feet
- A 2" × 6" × 8' board = 8 board feet
- A 4/4 (1") × 8" × 10' board = 6.67 board feet
Frequently Asked Questions
To calculate board feet, multiply the thickness (in inches) by the width (in inches) by the length (in inches), then divide by 144. The formula is: Board Feet = (Thickness × Width × Length) ÷ 144. If your length is in feet, multiply it by 12 first to convert to inches.
A board foot is the standard unit of measurement for lumber volume in North America. One board foot equals 144 cubic inches of wood—equivalent to a board that is 1 inch thick, 12 inches wide, and 12 inches long (1" × 12" × 12"). Lumber is typically priced per board foot.
An 8-foot 2×4 contains approximately 5.33 board feet. However, this uses nominal dimensions (2" × 4"). If using actual dimensions (1.5" × 3.5"), the same board contains about 3.5 board feet. Hardwood lumber is typically sold by actual dimensions.
4/4 (pronounced "four quarter") means the lumber is 1 inch thick in its rough-sawn state. The number represents quarters of an inch: 4/4 = 1", 5/4 = 1.25", 6/4 = 1.5", 8/4 = 2". This notation is standard for hardwood lumber pricing and allows for material lost during planing.
Nominal size is the name given to lumber (like "2×4"), while actual size is the true measurement after drying and planing. A nominal 2×4 actually measures 1.5" × 3.5". Softwood dimensional lumber uses nominal sizing, while hardwood is typically sold by actual thickness in quarters (4/4, 8/4, etc.).
Multiply the total board feet by the price per board foot. For example, if you have 25 board feet of walnut at $12 per board foot, the cost would be 25 × $12 = $300. Our calculator includes an optional price field to estimate costs automatically.
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