Board Foot Calculator
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About Board Feet
Hardwood isn't sold by the piece — walnut, maple, and oak are priced per board foot, a volume measure that lets a dealer price random widths and lengths on one scale. Misfigure it and a furniture project's lumber bill surprises you at the register; figure it right and you can compare dealers and species on equal footing.
Enter the board's three dimensions, how many pieces, and optionally the dealer's per-board-foot price. You get total board feet, the per-piece figure, cubic inches, and cost. For a cut list with mixed sizes, run each size and add the results.
Pricing a floor rather than project lumber? Coverage math lives in the Flooring Calculator
The Board-Foot Formula
One line, with the length conveniently in feet:
Board feet = thickness (in) × width (in) × length (ft) ÷ 12 1 board foot = 144 cubic inches = a 12″ × 12″ × 1″ slab
Worked example: a rough 8/4 maple board 8″ wide and 10′ long is 2 × 8 × 10 ÷ 12 = 13.33 board feet — at $8/bf, $106.67. Ten 8-foot 2×4s (actual 1.5″ × 3.5″) total 35 board feet.
Nominal vs Actual & Common Pieces
Surfaced softwood is named by its rough size but measures smaller. Board feet below use ACTUAL dimensions for an 8-foot piece — every value computed by this calculator:
| Nominal | Actual (in) | Board feet (8′ piece) |
|---|---|---|
| 1×4 | 0.75 × 3.5 | 1.75 |
| 1×6 | 0.75 × 5.5 | 2.75 |
| 2×4 | 1.5 × 3.5 | 3.50 |
| 2×6 | 1.5 × 5.5 | 5.50 |
| 2×8 | 1.5 × 7.25 | 7.25 |
| 2×10 | 1.5 × 9.25 | 9.25 |
| 2×12 | 1.5 × 11.25 | 11.25 |
| 4×4 | 3.5 × 3.5 | 8.17 |
Convenient coincidence: an 8-foot 2×anything works out to its nominal width × 0.5 − small change — a 2×8×8 is 7.25 bf because the actual width is 7.25″.
The Quarter System (4/4, 8/4…)
Hardwood thickness is quoted in quarters of an inch of ROUGH thickness: 4/4 (“four-quarter”) is 1″ rough, 5/4 is 1.25″, 6/4 is 1.5″, 8/4 is 2″, 12/4 is 3″. Dealers charge board feet on that rough thickness even after the board is surfaced down — S2S 4/4 stock actually measures around 13/16″, but you pay for the full 4/4. That's the convention, not a scam; the surfacing waste was real wood.
Practical buying notes: figure your project in finished dimensions, then buy the next quarter size up (a finished 1¾″ table leg needs 8/4 stock, not 6/4); add 15–30% for defects, grain matching, and test cuts — hardwood has knots and checks the grade allows; and confirm whether the dealer's tally is gross (before defect cutting) or net.
Frequently Asked Questions
How do I calculate board feet?
Thickness in inches × width in inches × length in feet, divided by 12. A 1″ × 6″ × 8′ board is 4 board feet. For multiple pieces, multiply by the count — the calculator handles the whole cut list one size at a time.
How many board feet in a 2x4x8?
By actual dimensions (1.5″ × 3.5″): 3.5 board feet. By nominal (2″ × 4″): 5.33. Construction lumber is normally priced per piece anyway — board-foot math matters most for hardwood, where the rough (nominal) thickness is the billing standard.
What does 4/4, 5/4, or 8/4 lumber mean?
Rough thickness in quarter inches: 4/4 = 1″, 5/4 = 1.25″, 8/4 = 2″. Hardwood is priced per board foot at that rough thickness even after surfacing thins the board — surfaced 4/4 typically measures about 13/16″.
Is a board foot the same as a linear foot?
No. A linear foot measures length only, regardless of the board's cross-section; a board foot measures volume. Trim and dimensional lumber quotes often use linear feet, hardwood uses board feet — converting between them requires the width and thickness.
How much does a board foot of hardwood cost?
It varies enormously by species, grade, thickness, and region — from a few dollars for local poplar to well past $20 for figured or exotic stock. That's why this calculator asks for your dealer's quote instead of pretending there's a standard price.
How much extra should I buy for a project?
15–30% over the cut-list total is the common woodworking allowance — it covers defects the grade permits (knots, checks, wane), grain and color matching, and machining test pieces. Complex grain-matched work sits at the high end.
Methodology. This calculator uses standard construction and material-estimation formulas. It is reviewed and maintained by the Vast Calculators editorial team.
Last updated · July 2026
Results are estimates for general use; verify critical figures independently.