Board Foot Calculator
This free board foot calculator turns a lumber cut list into the one number a lumberyard prices on. Unlike linear feet, a board foot is a measure of volume: a 1×12 holds three times the board feet of a 1×4 of the same length. Add as many board sizes as your project needs and the calculator totals them, with a waste factor for defects and cutting.
For dimensional softwood (2×4, 2×6, 4×4), board feet is figured on the nominal size by trade convention — a 2×4×8 is 5.33 board feet even though the surfaced board is 1½ × 3½ (DOC PS 20). For hardwood, switch a row to “custom” and enter the rough quarter thickness (4/4 = 1″, 5/4 = 1¼″, 6/4 = 1½″, 8/4 = 2″) and width, the way hardwood dealers measure and price it under NHLA rules.
Built on the board-foot definition — 144 cubic inches — with no signup and no pricing. The result includes MBF (thousand board feet, the wholesale unit) so you can compare quotes. When you have your cut list, feed it into the Framing, Deck, Stairs, or Trim calculator to lay out the lumber.
Board Foot Calculator
Build a lumber cut list and get the total board feet — the unit hardwood and rough lumber are priced in. Pick nominal sizes (2×4, 1×6) or enter custom hardwood thickness and width, add a waste factor, and see board feet, MBF, total pieces, and linear feet. Free, no signup.
Lumber cut list
Waste / overage (optional)
Calculation Formulas
The everyday board-foot formula. Thickness and width are in inches, length in feet; dividing by 12 converts the mixed units to board feet.
Example:
A 2 × 8 that is 10 ft long = 2 × 8 × 10 ÷ 12 = 13.33 BF.
When every dimension is in inches, divide by 144 — a board foot is 144 cubic inches (1 ft × 1 ft × 1 in).
Example:
A 1 × 6 board 96 in long = 1 × 6 × 96 ÷ 144 = 4 BF.
Add up the board feet of every line on your cut list. Different board sizes contribute very different amounts, so each is figured separately.
Example:
24 studs at 5.33 BF + 10 joists at 13.33 BF = 128 + 133.3 = 261.3 BF.
Dimensional softwood is figured on its nominal size by trade convention even though the surfaced board is smaller. A 2 × 4 is 1½ × 3½ actual but counts as 2 × 4 for board feet and pricing (DOC PS 20).
Example:
A 2 × 4 × 8 is 2 × 4 × 8 ÷ 12 = 5.33 BF, not the actual 1½ × 3½ volume.
Rough hardwood is sold by quarter-inch increments of its rough (pre-surfacing) thickness. Always figure board feet on the rough thickness you pay for, not the surfaced dimension.
Example:
A 4/4 board 6 in wide and 8 ft long = 1 × 6 × 8 ÷ 12 = 4 BF.
Linear feet measures length only; board feet measures volume. A 1 × 12 and a 1 × 4 of equal length have the same linear feet but the wide board is 3× the board feet. Never order hardwood by linear feet.
Example:
8 ft of 1 × 12 = 8 BF; 8 ft of 1 × 4 = 2.67 BF — same length, 3× the board feet.
Lumber is wholesale-priced per MBF — a thousand board feet. Convert your cut-list total to MBF to compare quotes or estimate cost from a per-MBF price.
Example:
2,500 BF = 2.5 MBF.
Rough lumber carries defects and needs cutting; add a waste factor before buying. Rough hardwood needs more (10–30%); surfaced (S4S) stock needs less.
Example:
261 BF at 15% waste = 300 BF to buy.
Standard Constants
| Constant | Value | Description |
|---|---|---|
| 1 board foot | 144 cubic inches | A board 1 ft × 1 ft × 1 in — the base unit of lumber volume. |
| 1 board foot | 12 in × 12 in × 1 in | Equivalent statement of the same volume. |
| 1 MBF | 1,000 board feet | The wholesale pricing unit for lumber. |
| 2 × 4 actual | 1½ × 3½ in | Surfaced size; board feet still uses the nominal 2 × 4 (DOC PS 20). |
| 4/4 hardwood | 1 in rough | Quarter-thickness system; 5/4 = 1¼, 6/4 = 1½, 8/4 = 2. |
| Standard board lengths | 8–16 ft (even) | Softwood is sold in even 2-ft increments; hardwood in random lengths. |
| Rough hardwood waste | 10–30% | Allowance for defects, grade cuts, and surfacing loss. |
| Surfaced (S4S) waste | 5–10% | Less allowance needed when boards are already milled four sides. |
Note: All calculations include appropriate waste factors based on project complexity and material type. Results are estimates and should be verified by professionals before purchasing materials.
American Softwood Lumber Standard (Nominal vs. Actual)(DOC PS 20-20)
View StandardThe US Department of Commerce voluntary product standard that defines softwood lumber sizes — why a 2 × 4 is actually 1½ × 3½ but is bought and board-footed as a 2 × 4.
Key Requirements:
- •Defines nominal vs. dressed (actual) dimensions for dimensional lumber.
- •Board feet and pricing use the nominal size by convention.
- •Sets moisture-content categories (S-GRN green vs. S-DRY kiln-dried).
NHLA Rules for the Measurement & Inspection of Hardwood(NHLA)
View StandardNational Hardwood Lumber Association rules governing how hardwood is graded and measured by the board foot.
Key Requirements:
- •Hardwood is measured rough by surface measure × thickness, in board feet.
- •Random widths are rounded to the nearest inch (or fraction) per the rules.
- •Grade (FAS, Select, No. 1 Common …) sets the yield of clear cuttings, not the board-foot count.
Hardwood Quarter Thickness System(NHLA thickness)
View StandardThe 4/4, 5/4, 6/4, 8/4 rough-thickness convention hardwood is ordered and priced in.
Key Requirements:
- •4/4 = 1″, 5/4 = 1¼″, 6/4 = 1½″, 8/4 = 2″ rough thickness.
- •Surfacing (S2S) removes roughly 3⁄16″–¼″, so 4/4 dresses to about 13⁄16″.
- •Board feet is figured on the rough thickness you pay for.
WWPA / Softwood Grading Rules(WWPA / WCLIB)
View StandardWestern Wood Products Association grading rules for dimensional and board softwood, used by lumberyards quoting by the board foot.
Key Requirements:
- •Defines structural grades (Select Structural, No. 1, No. 2, Stud).
- •Board feet for tallies and shipments uses nominal dimensions.
- •Length tallies are in even 2-ft increments for most dimensional stock.
NIST Handbook 44 — Volume Unit Definitions(NIST HB 44)
View StandardThe authority for the cubic-inch and board-foot units used in lumber trade.
Key Requirements:
- •1 board foot = 144 cubic inches.
- •1 cubic foot = 12 board feet of solid wood.
- •Tally and pricing units (BF, MBF) are derived from these definitions.
Standards Disclaimer: Standards and codes are subject to periodic updates. Always verify current requirements with local building authorities and professional engineers before beginning construction. Links provided are for reference only.
Softwood (Nominal) vs. Hardwood (Rough)
Two different board-foot conventions
Dimensional softwood is bought by nominal size and even lengths; hardwood is bought rough in quarter thicknesses and random widths and lengths. The board-foot math is the same, but what you measure differs — nominal for softwood, rough actual for hardwood.
Regional Examples:
Rough vs. Surfaced (S2S / S4S)
Milling removes material and changes yield
Rough boards are full quarter thickness; surfaced boards (S2S = two sides, S4S = four sides) are milled smaller. You pay board feet on the rough size, but the usable dressed size is less — plan extra for surfacing loss.
Regional Examples:
Green vs. Kiln-Dried
Moisture changes dimension and price
Green (S-GRN) lumber shrinks as it dries; kiln-dried (S-DRY / KD) is stable and costs more. Board feet is the same, but green boards lose width and thickness after installation.
Regional Examples:
Priced per Board Foot vs. per Piece
Big-box vs. lumberyard quoting
Home centers usually price dimensional lumber per piece; hardwood dealers and lumberyards price per board foot or per MBF. Convert your cut list both ways so you can compare apples to apples.
Regional Examples:
Random Widths & Lengths (Hardwood)
You buy what the tree gives
Most hardwood comes in random widths and lengths, not uniform boards. You order a total board-foot quantity by thickness and grade, then sort for your cuts — so add waste for the widths and lengths you can’t use.
Regional Examples:
Before You Build
- •Contact your local building department for specific requirements
- •Verify frost line depths, wind zones, and seismic requirements for your area
- •Check if permits are required and schedule required inspections
- •Consult with a local contractor familiar with local codes
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How to Use This Calculator
- Add a row for each board size in your project.
- Pick a nominal size (2×4, 1×6, 4×4 …) for dimensional softwood, or choose “Custom / hardwood” to enter your own thickness and width in inches.
- For hardwood, use the rough quarter thickness — 4/4 = 1″, 5/4 = 1¼″, 6/4 = 1½″, 8/4 = 2″ — and the rough width.
- Enter the length in feet and the quantity (number of identical pieces) for each row.
- Use “Add lumber row” for mixed cut lists — studs, joists, and trim in one calculation.
- Set a waste/overage factor — 10–15% for rough hardwood, 5–10% for surfaced (S4S) stock.
- Click Calculate to see total board feet, MBF, pieces, and linear feet, plus a per-row breakdown. Then open the Framing, Deck, or Stairs calculator to lay out the lumber.
Board Feet vs. Linear Feet — and Nominal vs. Actual
Two things trip people up. First, board feet is a volume, not a length: a 1×12 and a 1×4 of the same length have identical linear feet but the wide board is three times the board feet, so you can never order hardwood by linear feet. Second, dimensional softwood is board-footed on its NOMINAL size — a 2×4 counts as 2 × 4 even though the surfaced board is actually 1½ × 3½ (DOC PS 20 American Softwood Lumber Standard). Hardwood, by contrast, is figured on its rough (pre-surfacing) thickness in quarter increments under NHLA rules, because that is the thickness you pay for. Lumber is wholesale-priced per MBF — a thousand board feet — so the calculator shows that too for comparing quotes.
Frequently Asked Questions
How do you calculate board feet?
Multiply thickness (inches) × width (inches) × length (feet), then divide by 12. A 2×8 that is 10 feet long is 2 × 8 × 10 ÷ 12 = 13.33 board feet. If all three dimensions are in inches, divide by 144 instead, because a board foot is 144 cubic inches (a board 1 foot × 1 foot × 1 inch). This calculator lets you build a full cut list — add a row per board size with its length and quantity — and totals the board feet for you.
What is the difference between board feet and linear feet?
Linear feet measures length only; board feet measures volume. A 1×12 and a 1×4 of the same length have the same linear feet, but the 1×12 is three times the board feet because it is three times as wide. That is why hardwood is never sold by the linear foot — a wide board is worth far more than a narrow one of equal length. Use linear feet for trim and molding sold by the running foot, and board feet for hardwood and rough lumber priced by volume.
Do I use nominal or actual size for board feet?
For dimensional softwood (2×4, 2×6, 4×4), use the NOMINAL size by trade convention — a 2×4×8 is 5.33 board feet even though the surfaced board is actually 1½ × 3½ (DOC PS 20 American Softwood Lumber Standard). For hardwood, use the rough (pre-surfacing) thickness in quarter increments — 4/4 = 1″, 5/4 = 1¼″, 6/4 = 1½″, 8/4 = 2″ — and the rough width, because that is the size you pay for under NHLA rules. The calculator handles softwood automatically from the nominal size you pick, and lets you enter rough dimensions for hardwood.
What are hardwood lumber quarters (4/4, 5/4, 8/4)?
Hardwood is sold by rough thickness in quarter-inch increments. 4/4 ("four-quarter") is 1 inch, 5/4 is 1¼ inches, 6/4 is 1½ inches, 8/4 is 2 inches, and so on. You buy the rough thickness, then surfacing (S2S) removes about 3⁄16 to ¼ inch — so 4/4 dresses to roughly 13⁄16 inch. Board feet is always figured on the rough thickness you pay for, not the dressed size. In this calculator, choose "Custom / hardwood" and enter the rough thickness in inches.
How much waste should I add when buying lumber?
Add a waste factor for defects, grade cuts, and trimming. For rough hardwood, 10–30% is typical because you cut around knots, checks, and unusable widths, and surfacing removes material. For surfaced (S4S) softwood that is already milled four sides, 5–10% is usually enough. The calculator applies your waste percentage to the cut-list total. For furniture and millwork from random-width hardwood, lean toward the higher end so you are not short after cutting.
What is MBF in lumber pricing?
MBF means a thousand board feet — the unit lumber is wholesale-priced in (the M is the Roman numeral for 1,000). To convert, divide your board-foot total by 1,000: 2,500 board feet is 2.5 MBF. The calculator shows MBF alongside board feet so you can compare a per-MBF quote against a per-piece or per-board-foot price. Home centers usually price dimensional lumber per piece, while hardwood dealers and lumberyards price per board foot or per MBF.
Does this calculator show lumber prices?
No. Like every calculator on the site, it is pricing-free — it gives you quantities (board feet, MBF, pieces, linear feet), not dollar figures, because lumber prices move constantly by species, grade, and region. Take your board-foot total to a local lumberyard or hardwood dealer for a current per-board-foot or per-MBF quote. For laying out the actual lumber in a build, hand your cut list to the Framing, Deck, Stairs, or Trim calculator.