The Measure
A board foot is exactly 144 cubic inches. It represents a piece of wood 12" wide, 12" long, and 1" thick.
Lumber Board Feet Calculator
Board Details
Total Volume
Enter dimensions to calculate board feet.
5 Fun Facts About Lumber
Nominal vs. Actual
A "2x4" board isn't 2 inches by 4 inches. It starts that way (rough cut), but after drying and planing, it's 1.5" x 3.5".
Quarter Sawing
Quarter-sawn wood is cut radially from the log. It is more stable and warps less than plain-sawn wood, but it produces more waste.
Hard vs. Soft
Hardwood (oak, maple) comes from angiosperm (seed-bearing) trees, while softwood (pine, fir) comes from gymnosperms (cones).
CLT Skyscrapers
Cross-Laminated Timber (CLT) is a new super-strong plywood-like material that allows architects to build wooden skyscrapers.
How to use this board foot calculator
- Enter the quantity of boards you’re buying.
- Use actual (dressed) dimensions for thickness and width if you need precision; nominal 2×4 is typically 1.5" × 3.5".
- Enter the length in feet. The formula is (T × W × L) ÷ 12.
- Optionally add price per board foot to see estimated cost.
Tip: If the yard quotes in thousand board feet (MBF), multiply your result by 0.001 for MBF.
Nominal vs. actual sizes (cheat sheet)
2×4
~1.5" × 3.5" (SPF, KD). Multiply by length/12 for per-piece board feet.
2×6
~1.5" × 5.5" actual. Great for joists and rafters.
1× boards
Often ~0.75" thick after planing; widths vary (1×8 ≈ 7.25").
Hardwood/quarters
4/4 ≈ 1" rough; 8/4 ≈ 2" rough. Surfacing removes ~1/8–1/4".
Always check your supplier’s actual dimensions—mill, moisture, and surfacing change sizes and therefore board feet.
Board foot basics and ordering tips
A board foot (FBM or BF) measures volume, not length. One board foot is 144 cubic inches—the volume of a 1" × 12" × 12" board. When you buy lumber priced “per board foot,” you’re paying for volume; wider and thicker pieces grow board feet faster than length alone.
How to calculate board feet manually
The core formula is simple: (Thickness in inches × Width in inches × Length in feet) ÷ 12. Multiply by quantity to get a total. The calculator uses the same math but handles decimals, quantity, and optional cost automatically. If your yard quotes thousand board feet (MBF), divide your total board feet by 1,000.
Nominal vs. actual dimensions
Most framing lumber is sold by nominal size (e.g., 2×4) but dressed (planed) to a smaller actual size. A 2×4 is usually about 1.5" × 3.5", so its board feet are (1.5 × 3.5 × length_ft) ÷ 12. Using nominal numbers will overestimate volume and cost. Hardwood is often quoted in quarters (4/4, 5/4, 6/4, 8/4) where 4/4 ≈ 1" rough thickness; planed thickness will be slightly less.
Moisture, grade, and waste factors
Moisture content affects size and weight. Kiln-dried (KD) lumber shrinks compared to green, so rough-sawn green boards can plane down significantly. Higher grades (Select, #1) cost more and may reduce waste because of fewer defects. Always add a waste factor (5–15%) for cuts, knots, checks, or warping—especially on finish carpentry where matching grain and color matters.
Price per board foot and budgeting
Enter your price per board foot to estimate total cost. Prices often vary by species, grade, and length—longer clear boards can carry premiums. If a yard quotes by lineal foot, convert by multiplying their lineal price by board feet per lineal foot for that size (e.g., a surfaced 1×12 is roughly 0.75 bd ft per foot).
Planning cuts and layout
Before ordering, sketch a cut list. Use the fewest boards and lengths that cover your pieces while minimizing offcuts. Consider end-trimming for square edges and defects, and plan around knots for structural or visible faces. For glue-ups, buy extra to match color and grain. For structural framing, follow span tables and code—board feet alone doesn’t address load capacity.
Quick check: If your board feet feel high, confirm you used actual dressed sizes. If cost feels high, confirm whether the yard’s price is per board foot, per lineal foot, or per piece.