Lumber & Board Foot Calculator
Multi-size lumber takeoff
Enter board sizes, quantities, waste, density, and prices
Result
Calculation summary
Enter values to see the result
Board geometry preview
Thickness × width × length × pieces
Lumber lines
1
Purchase pieces with waste
9
Purchase board feet
72
Board 1
9 pieces
72 bd ft
The drawing shows the entered geometric model; it is not a cut plan, dressed-size table, grade rule, or structural member schedule.
How to use this calculator
- 1Add each distinct thickness, width, and length as its own lumber line so waste and whole-piece rounding remain visible.
- 2Choose whether the entered cross-sections are nominal trade sizes or actual measured sizes; the tool never silently converts between them.
- 3Enter requested pieces, a waste allowance, and optional price per piece or price per board foot for every line.
- 4Enable weight only when you have an appropriate density for the wood species, grade, moisture condition, and product.
Formula
Board feet = thickness (in) × width (in) × length (ft) × quantity ÷ 12
Equivalently, one board foot is 144 in³ or 0.002359737216 m³. Purchase quantity is rounded up separately for each distinct line after the entered waste allowance.
Calculation steps
- Convert each thickness, width, and length to meters and calculate the geometric volume per piece.
- Divide that volume by one board foot to obtain board feet per piece, then multiply by requested quantity.
- Apply waste to each line quantity and round up before calculating purchase board feet, volume, and linear length.
- If enabled, multiply purchase volume by the entered density and convert the estimated mass to the selected weight unit.
- For per-piece pricing, multiply whole purchase pieces by each line price; for board-foot pricing, multiply purchase board feet by each line price.
- Sum all line items without replacing the supplier’s tally, cut plan, nominal-size rules, or structural schedule.
Worked example
Eight nominal 2 in × 6 in × 8 ft boards equal 64 board feet. With 10% waste applied to that line, the purchase quantity rounds to nine boards and the purchase tally becomes 72 board feet.
Assumptions
- The calculator uses exactly the dimensions entered. Nominal entries produce a nominal geometric tally; actual entries produce an actual geometric-volume equivalent.
- Nominal and dressed dimensions can differ by product, species, moisture condition, region, and applicable standard. Measure or verify the supplier label when physical volume matters.
- Waste is converted to whole purchase pieces separately for every line; reusable offcuts, optimized nesting, saw kerf, defects, grade yield, and random-width hardwood tally rules are not modeled.
- Weight is a density-based estimate only. Wood density changes with species, moisture, treatment, engineered composition, and product variation.
- This is a quantity and volume tool, not a structural design tool; it does not select species, grade, spans, loads, member sizes, connections, treatment, or code compliance.
- Prices exclude tax, delivery, labor, hardware, finishes, milling, drying, grading, and supplier-specific rounding unless included in the entered line price.
Sources
- NIST Handbook 130 — 2026 Edition — National Institute of Standards and Technology
- American Softwood Lumber Standard PS 20 — National Institute of Standards and Technology
- Weights & Measurement — Lumber Labeling Guidance — American Wood Council
- How Do I Convert to Metric Lumber Sizes? — American Wood Council
Frequently asked questions
What is one board foot?
It is the volume equivalent of a board 1 inch thick, 12 inches wide, and 12 inches long: 144 cubic inches or 1/12 cubic foot.
Should I enter nominal or actual dimensions?
Use the basis used for the tally you need. Nominal sizes are common for purchasing and board-foot trade calculations; actual dimensions are appropriate for physical volume, fit, and density-based weight. Verify supplier labeling.
Why is waste rounded per line instead of after the total?
Different sizes are not interchangeable purchase pieces. Rounding each line prevents a fraction of one size from being hidden by another size.
Does the tool optimize cuts or reuse offcuts?
No. It adds whole pieces by line. A detailed cut list can reduce waste, while defects, grade, kerf, and required end trims can increase it.
Is the weight exact?
No. It is purchase volume multiplied by the density entered. Moisture, species, treatment, and product variation can materially change actual weight.
Can this calculator size structural lumber?
No. Member sizing requires loads, spans, species, grade, service conditions, connections, and applicable design rules.