Offline
No internet, no account required.
IRC
Validated against the standard.
PDF export
Pro-only. Generate professional reports.
$2.99 Pro
Lifetime unlock. No subscriptions.
How it works
Enter your values
Type in your inputs — the app fills code tables and constants for you, so there's nothing to look up.
Get a code-checked result
Instant answer with a clear PASS / FAIL and the exact IRC reference behind every number.
Save & export
Keep a history of calculations and export a clean PDF report to share or attach to a permit (Pro).
What this calculator does
Lumber is priced by the board foot, and quotes go wrong when the math does. This app converts dimensions to board feet, totals a cut list, and applies a waste factor so your order is right the first time.
The board-foot formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12
Use nominal dimensions (a 2x4 is figured as 2 by 4) the way the lumberyard prices it.
Worked example
Twenty 2x6 boards, 12 ft long: each = 2 × 6 × 12 ÷ 12 = 12 board ft; twenty boards = 240 board feet. Add a 10% waste factor and order for 264.
Related calculators
Count the pieces with the framing calculator and trim with the trim and molding calculator.
Lumber FAQ
What is a board foot?
A board foot is 144 cubic inches of lumber — one foot by one foot by one inch. The formula is thickness in inches times width in inches times length in feet, divided by 12.
Nominal or actual size?
Board feet are figured from nominal dimensions (a 2x4 counts as 2 by 4), which is how lumber is priced, even though the actual milled size is smaller.
Does it add a waste factor?
Yes. You can apply a percentage for offcuts and defects so the order covers real-world waste.
Does it work offline?
Yes, it runs 100% offline with no account. Free with rewarded ads; a one-time $2.99 Pro unlock adds PDF export and saved history.
Get Lumber Calculator on your phone
Free with rewarded ads · $2.99 lifetime Pro · iOS & Android. Works 100% offline on the job site.