Board foot calculator
Enter thickness, width and length (and how many pieces) to get board feet. Softwood lumber yards tally board feet from nominal sizes. Optional price per board foot estimates material cost. Defaults are ten 8-foot 2×4s.
How the calculator works
- Per piece: thickness (in) × width (in) × length (ft) ÷ 12.
- Stack: multiply by the number of pieces.
- Cost: total board feet × your price per BF, if entered.
Example: one nominal 2×4×8 ft = 2 × 4 × 8 ÷ 12 = 5.33 BF. Ten of them = 53.3 BF.
Nominal vs actual size
A “2×4” is a nominal name. After drying and surfacing, the dressed size is smaller—about 1½ × 3½ in for a standard dry softwood 2×4 under the American Softwood Lumber Standard (NIST Voluntary Product Standard PS 20). Commercial board-foot tally still uses the nominal thickness and width (and the actual length). Cubic (metric) measure uses dressed sizes.
| Nominal | Typical dressed (in) | BF for an 8 ft piece (nominal) |
|---|---|---|
| 1×4 | 0.75 × 3.5 | 2.67 |
| 1×6 | 0.75 × 5.5 | 4.00 |
| 2×4 | 1.5 × 3.5 | 5.33 |
| 2×6 | 1.5 × 5.5 | 8.00 |
| 2×8 | 1.5 × 7.25 | 10.67 |
| 2×10 | 1.5 × 9.25 | 13.33 |
| 2×12 | 1.5 × 11.25 | 16.00 |
| 4×4 | 3.5 × 3.5 | 10.67 |
Board feet vs linear feet
Yards often price framing lumber by the piece or by linear foot, and hardwood or specialty stock by the board foot. Use BF when comparing species or thicknesses on a volume basis; use LF (or piece count) when the SKU is sold that way. This calculator does not convert price lists—enter the unit your quote uses.
Related: stair stringer calculator, how to build stairs, fence installation cost (wood fence runs).
Sources
- NIST, American Softwood Lumber Standard (Voluntary Product Standard PS 20): board measure from nominal thickness × nominal width × length; dressed sizes in the standard’s tables; cubic measure uses dressed sizes.
- 7 CFR §1217.4: board foot definition for softwood lumber (nominal T×W; length actual; under 1 in thick counted as 1 in).
- University of Wisconsin Extension, What Is A Board Foot? (FEM 042): (T × W × L_ft) ÷ 12; note that surfaced lumber is smaller than nominal.