How to use this calculator
A board foot is 144 cubic inches of lumber: thickness (in) × width (in) × length (ft) ÷ 12, per piece. The trap is dimension basis: rough lumber is often billed on nominal dimensions, while dressed dimensional lumber measures smaller (a nominal 2 × 6 is actually about 1.5 × 5.5 in). This tool never silently substitutes one for the other — it computes from the dimensions you enter and labels the basis you selected.
Enter your own figures in the form above. A blank field is treated as missing — not as zero — so the tool will ask you to complete it. A genuine zero is accepted where it makes sense (for example, no HOA dues). Press Calculate for a breakdown, Load worked example to fill in the example below, or Reset to return to the defaults.
Formula and assumptions
Board feet per piece = thickness × width × length ÷ 12. Total board feet = per-piece board feet × pieces. Cost = total board feet × price per board foot.
Worked example
Worked example: 2 in × 6 in × 8 ft, 10 pieces, nominal billing basis. Board feet 80 (2 × 6 × 8 ÷ 12 = 8 per piece × 10). On an actual-dimension basis, entering 1.5 × 5.5 in instead would give 55 board feet — a different figure for a different convention, which is why the basis selector is part of the result.
Use the Load worked example button above to reproduce this example in the form, then change one input at a time to see what drives the result.
Limitations and common mistakes
Board feet measure volume, not strength, grade, species or suitability. The price basis must match the dimension basis: a price quoted per nominal board foot applied to actual-dimension board feet (or vice versa) will misprice the order.
Frequently asked questions
What is a board foot, in plain terms?
A volume: a board 1 inch thick, 12 inches wide and 12 inches long. Any shape with the same volume is also one board foot.
Why do nominal and actual differ?
Dressed lumber is surfaced after sawing, losing thickness and width. Rough lumber may be sold at full nominal size. Always confirm which basis a quote uses.
Does this work for sheet goods?
No. Plywood and panels are sold by sheet area, not board feet. Use area for those.
Sources
No external price, product or market data is used on this page. Every price, density, coverage and rate is a figure you enter, or a clearly labelled illustrative default in the form. Check product labels and supplier quotes for the figures that apply to your job.
Estimates only. Results from this calculator are not a loan offer, appraisal, engineering design, equipment selection or contractor quote.