How to use this calculator
- Thickness. Nominal thickness in inches (a "2-inch" 2×4 is actually 1.5 — use the nominal value for board-foot calculations).
- Width. Nominal width in inches.
- Length. Length in feet.
- Quantity & price. Number of boards plus optional $/board-foot for total cost.
Formula
Board Feet = (Thickness(in) × Width(in) × Length(ft) × Quantity) ÷ 12
Worked example
Ten 2×8 × 12 ft boards = (2 × 8 × 12 × 10) / 12 = 160 board feet. At $4.50/bd-ft, total cost is $720.
Common project sizes
Quick reference for the most common board feet calculator use cases. Use these as a sanity check on your calculator inputs.
| Project | Dimensions | Result |
|---|---|---|
| Bookshelf (3 shelves, 1×10×6 ft each) | 3 boards | 15.0 bd-ft |
| 6-board farmhouse table top (1×8×6 ft) | 6 boards | 24.0 bd-ft |
| Closet shelving (5 shelves, ¾×12×8 ft) | 5 boards | 30.0 bd-ft |
| Deck framing run (16 joists 2×8×12 ft) | 16 boards | 256 bd-ft |
2026 cost reference
Typical retail price range in the United States for board feet. Local pricing varies by region, supplier, and grade — confirm with two or three quotes before ordering.
Per board foot
$2 – $30+
Construction-grade SPF (spruce/pine/fir) is $2–$5/bd-ft as 2×4 and 2×6. Domestic hardwoods at the small mill: red oak $4–$8, hard maple $6–$10, cherry $9–$14, walnut $14–$22. Exotics (ipe, mahogany, ebony) start at $25/bd-ft and climb fast.
How we calculate this
Assumptions baked in
Board feet = (Thickness in inches × Width in inches × Length in inches) ÷ 144. Softwood framing (2×4, 2×6, 2×8…) uses NOMINAL dimensions because lumber is priced by nominal size at most yards; surfaced (S4S) hardwood uses ACTUAL planed dimensions because it's sold by the foot at the dressed size. The calculator switches behavior on the "surfaced" toggle.
Accuracy and margin of error
Exact for both calculations. The pitfall is selecting the wrong basis — entering a 2×4 with the "surfaced" toggle on (1.5 × 3.5 actual) computes 5.83 board feet per 8' stud, while the "nominal" toggle returns 8.0 board feet. Most lumber yards bill softwood framing at the nominal value, so use "nominal" unless your lumberyard explicitly says otherwise.
Edge cases this calculator does not handle
Hardwood is often sold in random widths and lengths (S2S surfaced two sides, S3S, S4S) — buy by the board, measure the actual face-side dimensions, and use the surfaced setting. Plywood and OSB are NOT sold by the board foot; they're sold by the sheet. Engineered lumber (LVL, glulam, I-joists) uses linear feet at a published cross-section.
Cited sources for this page
The figures and rules above are anchored to the following normative references. We link the underlying claim to its standard — not as generic SEO trust signals, but so you can audit any number on this page against a primary source.
Nominal vs. actual lumber dimensions and the board-foot definition (144 cubic inches) are codified in the American Lumber Standard PS 20 administered by the US Department of Commerce.
Source: American Lumber Standard Committee — Voluntary Product Standard PS 20
Tips for accurate results
- Hardwood is sold by the board foot (true thickness × actual width × length).
- Softwood (framing lumber) is usually sold by the linear foot or piece, not board feet.
- Always order 10–15% extra for cutting waste, defects, and miscalculation.
- Rough-sawn lumber yields about 70–80% finished after milling — factor that into hardwood orders.
Common mistakes to avoid
- Using actual planed dimensions for softwood framing — the lumberyard charges you for nominal. A 2×4×8 is 5.33 bd-ft, not 4.67.
- Forgetting waste — rip-and-glue projects yield 70–80% of the rough board feet you bought. Always order 15–20% extra for furniture-grade work.
- Mixing units — thickness and width are in inches, length is in feet. Get one wrong and the answer is off by 12×.
- Not negotiating bulk — most yards drop the per-board-foot price 10–20% over 100 bd-ft. Always ask before paying retail.
When to consult a pro
Board-foot math is something you do yourself — even a small contractor expects you to specify the lumber order in board feet for hardwoods or in board count for framing. Where a pro saves you money is on grade-out: an experienced furniture maker walking the rack can save 30% by selecting boards with usable yield instead of paying for premium-grade everywhere.