Enter Lumber Line Items
Example Data Table
| Item | Thickness (in) | Width (in) | Length (ft) | Qty | Board Feet Each | Board Feet Total |
|---|---|---|---|---|---|---|
| Studs | 1.5 | 3.5 | 8 | 20 | 3.5 | 70 |
| Planks | 1 | 6 | 10 | 12 | 5 | 60 |
| Beams | 3 | 7.25 | 12 | 4 | 21.75 | 87 |
Formula Used
Board feet is a lumber volume measure based on a 1-inch thick board that is 12 inches wide and 12 inches long.
- Per piece: BF = (Thickness(in) × Width(in) × Length(ft)) ÷ 12
- Alternate (all inches): BF = (Thickness(in) × Width(in) × Length(in)) ÷ 144
- Total: BFtotal = Σ(BF per piece × Quantity)
- Waste: BFwith waste = BFtotal × (1 + Waste% ÷ 100)
The calculator converts millimeters to inches and meters to feet before applying the formula, then reports approximate cubic feet and cubic meters using the waste-adjusted total.
How to Use This Calculator
- Enter one or more lumber rows with thickness, width, length, and quantity.
- Select units for each dimension; conversions happen automatically.
- Add a waste allowance to cover offcuts and defects.
- Optionally add a price per board foot to estimate cost.
- Click Calculate Board Feet to view results above the form.
- Use the CSV or PDF buttons to export your latest calculation.
Professional Article
What a Board Foot Measures
A board foot represents volume: one inch thick, twelve inches wide, and twelve inches long. That equals 144 cubic inches or 1/12 cubic foot. Lumber pricing often follows this unit because it normalizes different thicknesses and widths into one comparable value across species and grades. It aids truckload planning.
Thickness Matters Most
Thickness is entered in inches and is usually called “quarters” in yards: 4/4 ≈ 1 inch, 5/4 ≈ 1.25 inches, and 8/4 ≈ 2 inches. Planed boards measure slightly under nominal thickness, so using caliper measurements improves takeoffs and reduces order surprises. For rough-sawn stock, confirm full thickness first.
Nominal vs Actual Size
Dimensional lumber is labeled nominally (2×4, 2×6) but is sold at actual sizes after drying and surfacing. A “2×4” is commonly 1.5×3.5 inches. If you mix nominal labels with actual field measurements, your board‑foot totals can drift several percent on large orders. Keep one convention throughout.
Waste and Overage Planning
Add a waste factor for trimming, knots, defects, and layout changes. Typical ranges are 5–10% for straight framing, 10–15% for finish carpentry, and 15–25% for complex cabinetry. Apply waste to the total board feet, not each piece, to keep rounding consistent. Recheck waste after drawings are finalized.
Conversions and Mixed Units
This calculator accepts inches, feet, or meters for length. Remember: 1 foot = 12 inches and 1 meter ≈ 39.3701 inches. When converting, keep at least two decimal places for length to avoid undercounting long runs of smaller members like battens or strapping. Standardize units before sharing with the team.
Estimating Cost Quickly
If you know the price per board foot, cost is simply board feet × rate. For example, 85 board feet at 3.40 per board foot is 289.00. Track tax, delivery, and cut fees separately because they can add 5–20% beyond material price in many markets. Document currency and rate date for transparency.
Moisture and Movement Considerations
Moisture content affects both size and performance. Kiln-dried stock (often 6–12% moisture) is more stable than green lumber. Shrinkage across width can be several millimeters on wide boards, so for tight tolerances, base measurements on acclimated material. Allow extra stock when milling to final sizes.
Documentation for Site Control
Record each line item with thickness, width, length, quantity, and notes such as species, grade, and intended use. Exporting CSV supports audits and purchase orders, while a PDF snapshot is useful for approvals. Clear documentation reduces rework and improves supplier communication. Save revisions so changes are traceable later.
FAQs
1) What is the board-foot formula used here?
Board feet = (Thickness in inches × Width in inches × Length in feet × Quantity) ÷ 12. If you enter length in inches or meters, the calculator converts it to feet before applying the formula.
2) Does planing change board-foot calculations?
Yes. Surfacing reduces thickness and width slightly. For accurate purchasing and machining allowances, measure actual dimensions of planed boards, especially for hardwoods and finish work where small differences add up.
3) How do I handle nominal 2× lumber?
Use actual sizes when possible. A nominal 2×4 is commonly 1.5×3.5 inches, and a nominal 2×6 is commonly 1.5×5.5 inches. Consistency across all line items is more important than the label.
4) What waste factor should I apply?
Common waste ranges are 5–10% for framing, 10–15% for trim, and up to 25% for complex projects. Start conservative, then adjust after cut lists, joinery details, and defect allowances are known.
5) Can I estimate cost with this calculator?
Yes. Enter a price per board foot and the calculator multiplies it by total board feet. Add taxes, delivery, and shop fees separately for a complete project budget.
6) Why do totals differ from the supplier invoice?
Suppliers may use nominal thickness, sell in random lengths, round up to bundles, or apply minimum charges. Moisture and milling also affect actual dimensions. Compare your line items to their tally sheet and confirm measurement conventions.
7) What should I include in notes for each line item?
Record species, grade, intended use, and any special requirements like kiln-dried, treated, or appearance stock. Notes help you match quotes, avoid substitutions, and speed up reorders.