What Is a Board Foot?
A board foot (BF or FBM for "Foot Board Measure") is a specialized unit of volumetric measurement used in the lumber and timber industries across the United States and Canada. One board foot represents the nominal volume of a piece of wood that is 1 inch thick, 12 inches wide, and 12 inches long (1 foot long). In terms of volume, one board foot equals exactly 144 cubic inches or 1/12 of a cubic foot (approximately 0.00236 cubic meters).
Unlike dimensional softwood lumber (which is often sold by the linear piece at home improvement stores), hardwood species such as walnut, cherry, hard maple, and white oak are virtually always priced and sold by volume per board foot ($/BF). Measuring lumber by board feet ensures fairness because it accurately reflects the total yield of raw harvestable fiber regardless of how unevenly a sawyer sliced the raw log.
How to Calculate Board Feet: The Exact Formulas
To calculate board feet for any rectangular timber or rough-cut plank, you multiply thickness, width, and length. Depending on whether your board length is measured in feet or inches, use one of the two standard mathematical formulas below:
Standard for lumber yard orders where length is specified in standard 8′, 10′, or 12′ lengths.
Ideal for small woodworking projects, cut-offs, table tops, or precision craft cuts.
If you are purchasing multiple identical boards, simply multiply the individual board foot calculation by the total quantity: Total BF = Single Board BF × Quantity.
Step-by-Step Worked Example
Let us walk through a practical example of ordering raw black walnut for a dining table project. Suppose you need 4 boards, each measuring 2 inches thick, 8 inches wide, and 10 feet long:
- Identify dimensions: Thickness = 2", Width = 8", Length = 10', Quantity = 4.
- Multiply Thickness by Width: 2 × 8 = 16.
- Multiply by Length (in feet): 16 × 10 = 160.
- Divide by 12: 160 ÷ 12 = 13.33 Board Feet per board.
- Account for Quantity: 13.33 BF × 4 boards = 53.33 Total Board Feet.
- Calculate Cost (Optional): At $9.50/BF, total cost is 53.33 × $9.50 = $506.64.
Why Use Our Online Board Foot Calculator?
Multi-Board Tally in One Pass
Add multiple different board sizes to compile a complete cut-list or lumber order without resetting.
Quarter-Notation & Fractions
Type fractions like 8 1/4 or industry quarter notation (4/4, 6/4, 8/4, 12/4) directly into any field.
Imperial & Metric Support
Toggle between imperial inches/feet and metric millimeters/meters with auto-conversion.
Instant Sharing & Clean Printouts
Copy tally text, save to browser history, or print an order slip for your lumber yard.
Common Lumber Sizes & Board Footage
In architectural framing and construction lumber, sizes like 2×4, 2×6, and 4×4 are referenced by their nominal dimensions. When calculating board footage for framing or estimating lumber loads, board footage is always computed against these nominal numbers. For example, a 2×4 contains 0.667 board feet for every linear foot of length, meaning an 8-foot 2×4 stud equals exactly 5.33 BF.
Tips for Accurate Lumber Estimates
When ordering lumber from a sawmill or commercial yard, always include a waste factor. Because rough-sawn boards contain natural defects, knots, sapwood, checking, and bow, woodworkers typically add 15% to 20% extra board footage for standard cabinet work, and up to 30% for complex curved furniture or matching grain patterns. Ordering a little extra avoids running short on matching stock mid-project.