Board Feet Calculator
Calculate board feet from lumber thickness, width, and length.
Add multiple pieces to get total footage and estimated cost for any woodworking project.
Board feet (BF) is the standard North American unit for measuring and pricing lumber volume. One board foot equals a piece of wood 1 foot long × 1 foot wide × 1 inch thick — or any combination of dimensions with the same total volume.
Board feet formula: Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12
Or equivalently, with length in inches: Board Feet = (Thickness × Width × Length) ÷ 144
Variable definitions:
- Thickness — measured in inches (use nominal thickness for rough lumber; actual thickness for S4S dressed lumber)
- Width — measured in inches
- Length — measured in feet (or divide inches by 12)
- Dividing by 12 — converts the inch-based area to a per-foot-of-length volume unit
Nominal vs. actual dimensions — critical distinction: Lumber is sold by nominal (name) size but the actual dressed size is smaller:
- “1×4” = 0.75″ × 3.5″ actual
- “2×4” = 1.5″ × 3.5″ actual
- “2×6” = 1.5″ × 5.5″ actual
- “2×8” = 1.5″ × 7.25″ actual
- “4×4” = 3.5″ × 3.5″ actual
Board feet calculations for pricing use nominal dimensions; structural calculations use actual dimensions.
Price from board feet: Total Cost = Board Feet × Price per Board Foot
Rough-sawn hardwood pricing (US average):
- Pine: $2–$4/BF
- Oak: $5–$9/BF
- Walnut: $10–$18/BF
- Cherry: $8–$14/BF
- Maple: $6–$10/BF
- Exotic (teak, mahogany): $15–$40/BF
Waste factor — add 10–20% for kerf loss, defects, and miscuts.
Worked example: You need to build shelves using 1×8 oak boards (nominal). You require 5 pieces, each 8 feet long.
- Board feet per piece: (1 × 8 × 8) ÷ 12 = 5.33 BF
- Total board feet: 5 × 5.33 = 26.67 BF
- Add 15% waste: 26.67 × 1.15 = 30.67 BF (buy 31 BF)
- Cost at $7/BF: 31 × $7 = $217
Linear feet conversion: For framing lumber where length (not volume) matters: 1 linear foot of 2×4 = (2 × 4 × 1) ÷ 12 = 0.667 BF.