LUMBER
BOARD FEET
BF = T·W·L ÷ 12
in
in
ft
pcs
RESULT
—
—
T and W in inches, L in feet. One board foot = 144 cubic inches of lumber.
About this calculator
This board feet calculator helps you spec a lumber order. One board foot equals 144 cubic inches (a board 1 inch thick × 12 inches wide × 1 foot long). Use nominal sizes for the thickness and width inputs (a 2x4 is 1.5 × 3.5 actual, but 2 × 4 nominal — always use nominal for board feet). Length is in feet.
Common questions
What's the difference between nominal and actual lumber size?
A "2×4" measures 1.5"×3.5" actual. Nominal sizes are what lumber was before drying and planing. Use nominal for board feet calculations and ordering; use actual when measuring fits and clearances.
How much does a board foot of lumber cost?
Construction-grade 2× SPF: $0.60–1.20/BF. Premium framing (Doug fir, southern yellow pine): $1–2/BF. Hardwoods at the lumber yard: oak $4–8/BF, walnut $10–15/BF, maple $5–9/BF. Big-box stores price by piece, not BF.
How do I convert linear feet to board feet?
Multiply nominal thickness × nominal width × length (in feet) ÷ 12. A 2×6 that's 8 ft long is 2 × 6 × 8 ÷ 12 = 8 board feet. This calculator does it for you across multiple pieces.