Lumber / Board Feet Calculator
Calculate board feet from lumber dimensions. Use presets for common nominal sizes or enter custom dimensions.
Actual: 1.5" × 3.5"
Board Feet (per piece)--
Total Board Feet--
Cubic Feet--
Cubic Meters--
About Board Feet
A board foot is a unit of volume for lumber equal to 144 cubic inches — equivalent to a board 1 inch thick, 12 inches wide, and 1 foot long. The formula is: (thickness × width × length) / 12 where thickness and width are in inches, and length is in feet. Note that nominal lumber sizes (like "2×4") are larger than actual dimensions — a nominal 2×4 actually measures 1.5" × 3.5" after planing and drying.
FAQ
What is a board foot?
A board foot (BF) is a unit of lumber volume equal to 144 cubic inches — a board 1" thick × 12" wide × 1' long. It's the standard unit for pricing hardwood lumber. Formula: (Thickness in × Width in × Length ft) ÷ 12.
Why are nominal sizes different from actual sizes?
Lumber starts at nominal size when rough-sawn, then loses about ½" to ¾" in each dimension during planing (smoothing) and kiln drying. A "2×4" starts as 2"×4" rough but finishes at 1.5"×3.5" actual. Board foot calculations use nominal dimensions.
How do I calculate cost from board feet?
Hardwood is typically sold per board foot. Multiply total board feet by the price per BF. For example, 20 BF of red oak at $6.50/BF = $130.00. Softwood (like pine, spruce) is usually sold by the piece or linear foot instead.
Does this use nominal or actual dimensions?
This calculator uses nominal dimensions for board foot calculations, which is the industry standard. The actual (smaller) dimensions are shown for reference. When buying lumber, board feet are always based on nominal size.