Board Feet Calculator
Board Feet — Calculating Lumber for Any Project
Board feet is the standard unit for buying and selling hardwood lumber in North America. Unlike softwood lumber which is sold by the linear foot or piece, hardwood is priced per board foot — a volume measurement that accounts for thickness, width, and length together.
How to Use This Calculator
Enter the thickness (in inches), width (in inches), length (in feet), and quantity of boards. Add a waste factor for end cuts, defects, and mistakes, and a price per board foot for a cost estimate. Hit Calculate Board Feet to see total board footage and estimated material cost.
The Board Foot Formula
Using the defaults — 1" thick × 6" wide × 8 ft long × 10 boards:
- BF per board: (1 × 6 × 8) ÷ 12 = 4 board feet
- Net total: 10 × 4 = 40 board feet
- With 10% waste: 44 board feet
- Cost at $3.50/BF: $154
Nominal vs. Actual Lumber Dimensions
Lumber is sold by nominal dimensions, but the actual dressed (surfaced) size is smaller due to milling:
- 1×4 nominal = 0.75" × 3.5" actual
- 1×6 nominal = 0.75" × 5.5" actual
- 2×4 nominal = 1.5" × 3.5" actual
- 2×6 nominal = 1.5" × 5.5" actual
- 4×4 nominal = 3.5" × 3.5" actual
Always use actual dimensions when calculating board feet for accurate volume. Using nominal dimensions will overstate your order by 20–25%.
Frequently Asked Questions
Why is hardwood sold by board feet instead of linear feet?
Hardwood comes in random widths and thicknesses — unlike dimensional softwood which is pre-cut to standard sizes. Board feet accounts for all three dimensions (thickness × width × length), giving a consistent volume-based price regardless of the specific board dimensions. Two boards with the same board footage contain the same volume of wood.
What waste factor should I use?
10% is standard for straightforward projects with clean, defect-free lumber. Use 15–20% for rough-sawn lumber with more knots and defects, projects with many angled cuts, or if you're an inexperienced woodworker. Hardwood is expensive — buy enough the first time since matching grain and color on a second purchase is difficult.
How do I convert board feet to linear feet?
Linear feet = Board feet × 12 ÷ (Thickness × Width). For a 1" × 6" board: LF = BF × 12 ÷ (1 × 6) = BF × 2. So 20 board feet of 1×6 = 40 linear feet. The calculator shows total linear feet in the results automatically.
What's the difference between a board foot and a running foot?
A running foot (or linear foot) is simply one foot of length, regardless of width or thickness — used for trim, molding, or pre-sized softwood. A board foot is a volume unit: 1" × 12" × 12" = 1 board foot. The same 1 linear foot of a 2×4 contains 0.67 board feet (1.5" × 3.5" × 1' ÷ 12 = 0.4375 BF). Hardwood dealers price in board feet; home centers typically price softwood by the piece or linear foot.
How do I read rough-sawn hardwood thickness?
Rough-sawn lumber is sold in nominal thickness increments of ¼ inch, called "quarters" — 4/4 (1 inch), 5/4 (1.25"), 6/4 (1.5"), 8/4 (2"), 12/4 (3"). After surfacing, a 4/4 board ends up about ¾" thick. For board foot calculations, use the rough-sawn nominal thickness (4/4 = 1"), not the surfaced thickness — that's how lumber dealers price. Using ¾" instead of 1" would undercount your material order by 25%.