Lumber & framing calculator

Board foot calculator

Lumber board-foot quantity from stated thickness, width, length, piece count and allowance.

Calculator result and formula

Planning board footage: 110 board ft

Formula: Thickness (in) × width (in) × length (ft) × quantity ÷ 12 × (1 + waste)

Formula ID: LUM-BF-001 · Version 1.0.0 · Published · Last reviewed Aug 26, 2026.

Inputs

  • Lumber thickness: Use the pricing thickness basis supplied by the lumber seller Default: 2.
  • Lumber width: Use the pricing width basis supplied by the lumber seller Default: 6.
  • Board length: Length of one board Default: 10.
  • Number of boards: Count identical boards Default: 10.
  • Waste factor: Allowance for defects, cuts and selection Default: 10.

How this calculator works

This calculator applies the standard board-foot volume formula to stated lumber dimensions and piece count, keeping its purchase allowance visible.

  1. Use the thickness and width basis used by the seller for pricing.
  2. Enter board length and count for identical pieces.
  3. Add a documented allowance for selection, defects or cuts before obtaining supplier pricing.

Worked example: Example: ten 2 in × 6 in × 10 ft boards contain 100 board feet before a 10% allowance, resulting in 110 planning board feet.

Assumptions and limitations

  • Board-foot arithmetic uses the stated thickness and width pricing basis, not an assumed nominal or actual size.
  • Metric dimensions are converted to inches before the board-foot formula.
  • Waste is a transparent planning allowance and supplier tally rules can differ.

Common mistakes to avoid

  • Confirm the measurement basis and units before using the result.
  • Keep waste or allowance visible and adjust it for the actual job conditions.
  • Confirm supplier packaging, delivery increments, specifications, and final site requirements before ordering.

Calculator disclaimer

This planning calculator does not determine structural design, code compliance, installation requirements, or guaranteed pricing. Confirm final requirements with the appropriate responsible professional, authority, manufacturer, and supplier.

Formula review and sources

Internal QA complete · independent external review pending · 1 source reference.

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