Board Foot Calculator
This board foot calculator works out board footage from thickness, width, and length — the volume-based unit lumber yards use to price rough-sawn and hardwood stock. It also works as a board feet calc, board foot calc, or boardfoot calculator for measured lumber dimensions, multiple pieces, and an optional cost estimate.
(T × W × L) ÷ 12Same length, very different amounts of wood
A linear foot alone reveals very little about how much wood you’re actually buying — an 8-foot 1×4 and an 8-foot 2×12 are both “8 feet,” yet the 2×12 contains roughly six times more material. The board foot — sometimes searched as a board feet calc, a board foot calc, or a boardfoot calculator — closes that gap by measuring true volume instead of length: thickness multiplied by width multiplied by length, condensed into a single figure lumber yards use to price rough-sawn and hardwood stock consistently, regardless of a board’s shape.
This calculator handles the board footage arithmetic automatically, along with the nominal-versus-actual sizing confusion that trips up most DIY cut-list math. Pick a common dimensional size from the shortcuts above, or enter your measured dimensions directly, and you’ll get board feet per piece, a project total, and an estimated cost once you enter a price per board foot.
Whether you’re pricing a single hardwood board or a full material estimate, treat this as a board footage calculator first and a cost estimator second. Supplier billing conventions can differ, especially for hardwood tally, so confirm the measurement basis used on the quote.
At a glance
- Formula:(Thickness × Width × Length) ÷ 12.
- Nominal vs. actual:A 2×4 is really 1.5×3.5 in.
- Scales by quantity:Per-piece BF × pieces = project total.
- Hardwood pricing:Sold in 4/4, 5/4, 8/4 thickness steps.
The board foot formula, explained
A board foot is a volume, not a length: one board foot equals a piece measuring 12 inches long, 12 inches wide, and 1 inch thick (144 cubic inches), regardless of the actual shape being measured.
The board foot formula
Board Feet = (Thickness in × Width in × Length ft) ÷ 12. This calculator expects length in feet; if you only know length in inches, divide the result by 12 a second time.
Nominal vs. actual lumber size
Under NIST PS 20-25, common dry dressed dimension lumber has minimum dressed sizes such as 1.5×3.5 inches for a nominal 2×4. Green sizes and some species/products can differ, so confirm the applicable size for your stock.
Why board feet instead of linear feet
Board feet account for thickness and width in addition to length, so the figure reflects actual volume — a distinction that matters when comparing cost between boards of different dimensions.
Pricing multiple pieces
Board feet per piece multiplied by quantity gives you a project total, which is what makes this useful for pricing an entire cut list rather than one board at a time.
See the board foot formula in action
These realistic illustrative examples use transparent dimensions and arithmetic. They are not claims about a particular purchase or supplier invoice.
Five dry dressed 2×6 boards, 8 feet long
Per piece: (1.5 × 5.5 × 8) ÷ 12 = 5.50 BF. Five pieces total 27.50 BF.
Geometric estimate for a measured hardwood board
(1 × 6 × 6) ÷ 12 = 3 BF. A commercial hardwood tally may use NHLA/supplier conventions instead of finished measured dimensions.
Where board footage estimates go wrong
Mixing nominal and actual sizes in the same calculation
Combining a nominal 1.5×5.5 thickness with a supplier’s actual-size pricing (or the reverse) throws off both the board feet figure and the resulting cost. Confirm which convention your supplier uses before entering numbers.
Entering length in inches instead of feet
This calculator expects length in feet. Board footage will be inflated by a factor of 12 if inches are entered without first converting.
Not rounding hardwood thickness up to the nearest quarter-inch
Hardwood trade measurement can use standard thickness and surface-measure rules rather than the finished measured thickness alone. If you are reconciling a supplier tally, follow the applicable NHLA/supplier measurement convention instead of assuming a finished-size geometric calculation will match it.
Forgetting a waste factor on a cut list
Board feet math alone doesn’t account for saw kerf, defects, or offcuts — projects may need extra material for saw kerf, defects, grain matching and offcuts. Choose any waste allowance from the needs of the specific project rather than relying on one universal percentage.
Nominal vs. actual dimensional lumber sizes
Standard S4S (surfaced four sides) sizes for common softwood construction lumber sold in the US.
| Nominal | Actual (in) |
|---|---|
| 1×4 | 0.75 × 3.5 |
| 1×6 | 0.75 × 5.5 |
| 1×8 | 0.75 × 7.25 |
| 1×10 | 0.75 × 9.25 |
| 1×12 | 0.75 × 11.25 |
| 2×4 | 1.5 × 3.5 |
| 2×6 | 1.5 × 5.5 |
| 2×8 | 1.5 × 7.25 |
| 2×10 | 1.5 × 9.25 |
| 2×12 | 1.5 × 11.25 |
| 4×4 | 3.5 × 3.5 |
Board foot calculator: common questions
What exactly is a board foot?+
Should I use nominal or actual dimensions?+
Is board foot the same as square foot or linear foot?+
How is hardwood board footage priced differently?+
Why isn’t my 2×4 actually 2 inches by 4 inches?+
How do I calculate board feet by hand?+
Other tools for framing & lumber takeoffs
These are the calculators on calcsdone that pair most naturally with board footage — all from the same Framing & Structural group.
Formula references
The core geometric formula is shown on the page. NIST is used for common dry dressed softwood sizes, while NHLA is used to explain why commercial hardwood tally can follow different measurement conventions.
- NHLA Rules for the Measurement & Inspection of Hardwood & Cypress — Measurement & Tally
- Voluntary Product Standard PS 20-25 — American Softwood Lumber Standard. National Institute of Standards and Technology (NIST), U.S. Department of Commerce.
- NHLA Grading Rules. National Hardwood Lumber Association.
- CalcsDone Methodology