Lumber Board Feet Calculator
This calculator computes board feet and total volume from user-supplied lumber dimensions: thickness (inches), width (inches), length (feet), and piece count. It is intended for quick estimating, purchasing checks, cutting lists, and inventory reconciliation.
Results reflect measured (actual) dimensions. If you work with nominal lumber sizes (for example '2x4' nominal = 1.5" × 3.5" actual), enter the actual finished dimensions to get accurate board-foot values. See methodology for guidance on measurement accuracy, waste allowance, and regulatory references.
Governance
Record 0c2359c76cc1 • Reviewed by Fidamen Standards Committee
Inputs
Results
Board Feet per Piece (BDFT)
4
Total Board Feet (BDFT)
4
Total Volume (cubic ft)
0.3333
| Output | Value | Unit |
|---|---|---|
| Board Feet per Piece (BDFT) | 4 | board foot |
| Total Board Feet (BDFT) | 4 | board foot |
| Total Volume (cubic ft) | 0.3333 | cubic foot |
Visualization
Methodology
Board feet are an industry volume unit for lumber. The standard calculation uses thickness in inches, width in inches, and length in feet. Board feet per piece = (thickness_in × width_in × length_ft) ÷ 12. Total board feet = board feet per piece × pieces.
Use calibrated measuring tools (steel tape or calipers) and measure across the widest face for width and the thickest point for thickness. When working with nominal lumber sizes, convert to actual dimensions (nominal → dressed sizes) before calculating. Allow for saw kerf, planing, and shrinkage when estimating required purchase quantities.
For professional and safety standards, consult federal and laboratory references for units and measurement practice. See citations for NIST unit guidance and the USDA Forest Products Laboratory for timber measurement and nominal-to-actual sizing guidance.
Worked examples
Example 1 — Single 2x6 @ 8 ft (use actual size): actual thickness 1.5 in, width 5.5 in, length 8 ft. Board feet per piece = (1.5 × 5.5 × 8) ÷ 12 = 5.5 BDFT. Ten pieces = 55 BDFT; total cubic feet ≈ 4.583 ft³.
Example 2 — 50 boards of 3/4" × 10" × 12 ft: per piece BDFT = (0.75 × 10 × 12) ÷ 12 = 7.5 BDFT. Total = 7.5 × 50 = 375 BDFT.
F.A.Q.
What is a board foot?
A board foot is a volume unit equal to 1 inch × 12 inches × 12 inches (equivalently 12 board inches), commonly used in the lumber trade to quantify dimensional lumber.
Should I enter nominal or actual dimensions?
Enter actual (measured) dimensions for accurate results. Nominal sizes (e.g., '2x4') refer to rough or pre-dressed dimensions; finished sizes are smaller (a finished 2x4 is typically 1.5" × 3.5"). Use actual sizes to calculate board feet precisely.
How should I round results?
Round board-foot results consistent with your procurement practice. For quick estimates round to two decimal places. For billing or inventory, follow the rounding rules used by your supplier or job specifications (some operations round to the nearest 1/8 or 1/10 BDFT).
How do I account for waste, kerf, and defects?
Include a waste allowance based on cutting pattern and saw type. Typical allowances range from 5% to 15% depending on species, joinery, and yield. Account for saw kerf (blade width) when planning cuts and deduct expected defect percentages when reconciling usable board feet.
Can I convert board feet to cubic meters or other units?
Yes. Board feet can be converted to cubic feet (1 BDFT = 1/12 ft³) and then to cubic meters using standard unit conversion factors. For regulatory or lab-grade conversions, consult NIST unit guidance for exact factors.
How accurate will this calculator be compared to a scale or invoices?
Accuracy depends on the precision of your measurements and whether you used nominal or actual dimensions. This tool uses mathematical definitions; differences from scale/invoice values arise from rounding, nominal sizing, moisture content, and vendor-specific measurement conventions. When accuracy matters for trade or compliance, verify with calibrated instruments and reference standards.
Does moisture content affect board feet?
Board-foot calculations are geometric and do not change with moisture content. However, moisture affects weight and may change dimensions slightly due to shrinkage or swelling; allow for this when moving from green to dried stock.
Sources & citations
- NIST — Units and Standards Information — https://www.nist.gov
- USDA Forest Products Laboratory — Wood Handbook and measurement guidance — https://www.fpl.fs.usda.gov
- MIT OpenCourseWare — Materials and structural references — https://ocw.mit.edu
- Occupational Safety and Health Administration (OSHA) — Lumber handling safety — https://www.osha.gov
- ACI — American Concrete Institute Standards — https://www.concrete.org/publications/typesofpublications/standards(codesandspecs).aspx
- ACI 211.1-91 — Standard Practice for Selecting Proportions for Concrete — https://www.concrete.org/
- ASTM International — Construction Standards — https://www.astm.org/
Further resources
Related tools
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 0c2359c76cc1What changed (latest)
v1.0.0 • 2025-11-10 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-10 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Engine
v1.0.0
Data
Baseline (no external datasets)
Content
v1.0.0
UI
v1.0.0
Governance
Last updated: Nov 10, 2025
Reviewed by: Fidamen Standards Committee (Review board)
Credentials: Internal QA
Risk level: low
Reviewer profile (entity)
Fidamen Standards Committee
Review board
Internal QA
Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person
Semantic versioning
- MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
- MINOR: New features or fields that do not change existing outputs for the same inputs.
- PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.
Review protocol
- Verify formulas and unit definitions against primary standards or datasets.
- Run golden-case regression suite and edge-case suite.
- Record reviewer sign-off with credentials and scope.
- Document assumptions, limitations, and jurisdiction applicability.
Assumptions & limitations
- Uses exact unit definitions from the Fidamen conversion library.
- Internal calculations use double precision; display rounding follows the unit's configured decimal places.
- Not a substitute for calibrated instruments in regulated contexts.
- Jurisdiction-specific rules may require official guidance.
Change log
v1.0.0 • 2025-11-10 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 14198d1b43dc