Lumber is priced by the board foot — a volume unit equal to 144 cubic inches. Multiply thickness × width (inches) × length (feet), divide by 12, to get board feet per piece.
The example
A 2×6, 8 ft long.
| A | B | |
|---|---|---|
| 1 | Item | Value |
| 2 | 2 × 6 × 8 ft | — |
| 3 | Board feet | → 8.0 |
The formula
The formula:
How it works
How it works:
- A board foot is 1 inch thick × 12 inches wide × 1 foot long = 144 cubic inches.
- The shortcut:
thickness(in) × width(in) × length(ft) / 12. - For multiple pieces, multiply by the count; for total cost, × price per board foot.
- Use nominal dimensions (a “2×6”) for pricing, even though the actual size is smaller.
Nominal vs actual: a “2×4” actually measures 1.5×3.5 inches after milling, but lumber is priced by nominal board feet. Use the nominal numbers for cost estimates and the actual numbers only when you need real volume or fit. Mixing them is a classic estimating error.
Try it: interactive demo
Thickness, width (in), length (ft), count.
Variations
Many pieces
× count:
Total cost
Board feet × price:
From a cut list
Sum a column:
Pitfalls & errors
Length in feet. Thickness and width are inches, length is feet — the /12 assumes it.
Nominal for pricing. Use nominal sizes; actual milled sizes are smaller.
Per piece. Multiply by count for the order total.
Practice workbook
Frequently asked questions
How do I calculate board feet in Excel?
What is a board foot?
Should I use nominal or actual lumber sizes?
Stop fighting formulas. Learn them in a day.
This recipe is one of hundreds of real-world formulas we teach. Our Excel Formulas & Functions class covers lookups, logic, text, and dynamic arrays hands-on — live in Dallas–Fort Worth, Houston, Austin, Oklahoma City, Denver, or online.
See the Formulas & Functions Class