Home & Construction
Calculate board feet for any board or a whole lumber order — and what it costs at your local price per board foot.
A board foot is a unit of volume equal to a board 1 inch thick, 12 inches wide, and 12 inches long — 144 cubic inches. The formula is:
Board feet = (thickness in inches × width in inches × length in inches) ÷ 144
If your length is in feet instead, use: (thickness × width × length in feet) ÷ 12.
Two things trip people up. First, nominal vs. actual size: a store-bought "2×4" actually measures 1.5″ × 3.5″, and board feet at most lumber yards are billed on the nominal size, while hardwood dealers bill on the actual (rough) dimensions before surfacing. Use the preset menu above for true actual sizes, or enter the nominal numbers if that's how your yard bills. Second, hardwood is often sold in quarters — 4/4 (said "four-quarter") is 1″ rough, 5/4 is 1.25″, 8/4 is 2″. Add 10–20% waste for cutting, defects, and grain matching; pros rarely buy the exact figure.
| Nominal size | Actual size | Board feet per foot of length |
|---|---|---|
| 1×4 | 0.75″ × 3.5″ | 0.22 BF/ft |
| 1×6 | 0.75″ × 5.5″ | 0.34 BF/ft |
| 1×12 | 0.75″ × 11.25″ | 0.70 BF/ft |
| 2×4 | 1.5″ × 3.5″ | 0.44 BF/ft |
| 2×6 | 1.5″ × 5.5″ | 0.69 BF/ft |
| 2×8 | 1.5″ × 7.25″ | 0.91 BF/ft |
| 4×4 | 3.5″ × 3.5″ | 1.02 BF/ft |
From the Toolkit Shop
Board feet is the takeoff. The estimate it lands in — with markup, tax and the deposit figured — is the Contractor Job Cost System — one spreadsheet, no subscription.
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