- Keep the board face width separate from the installation gap.
- Physical solid volume also needs actual thickness; supplier tally may follow a different basis.
- No installation gap or stock dimension is prescribed by this schematic.
Name the measurement
A linear foot measures length. A square foot measures area. A board foot is a volume unit equal to 144 cubic inches. The quantity worksheet computes physical volume from the actual dimensions you enter and reports its equivalent in board feet. This is deliberately called actual-volume BF; it is not a prediction of the supplier’s invoice.
Nominal labels need a separate basis
A nominal product description is a trade designation, not a promise that both measured dimensions equal the numbers in the label. NIST PS 20 describes softwood measurement and tally conventions, including nominal board measure and dressed cubic measurement. Do not apply one universal nominal conversion to every hardwood, imported profile or remanufactured product.
- Obtain actual thickness and face width for physical calculations.
- Record the nominal or trade label in the purchase description.
- Ask which dimension basis the quoted unit price uses.
Reconcile before comparing prices
Two quotes can use different tally bases even when they describe similar-looking material. Compare total delivered scope and written quantities rather than converting a unit price without its measurement basis. Surface machining, rough thickness, rounding rules and minimum lengths may affect the commercial tally. The calculator does not certify grading or trade measurement compliance.
Worked planning example
Twelve boards at actual 1.5 × 5.5 × 96 inches contain 66 actual-volume board feet. They have 96 linear feet of length and 44 square feet of face area. A nominal tally may differ; do not use 66 BF as an invoice correction without the supplier’s measurement agreement.
Common questions
Should I enter nominal 2×6 dimensions?
Use the actual thickness and width for this physical-volume worksheet. Keep the nominal description alongside the order, not as a hidden substitution.
Does face area equal installed coverage?
Only for the stated flat face dimensions without gaps, overlaps, grooves or cut loss. Installed coverage is an assembly question.
Evidence & limits
- Calculation method: dimensional arithmetic and conservative first-fit packing
- NIST PS 20-25 — measurement, tally and softwood size basis
Reviewed September 13, 2026. Sources support their stated technical principles; this site's workflows and hypothetical examples are not product tests, supplier approvals or independently reviewed project records.