Board Foot Calculator
A board foot is the standard volume unit for hardwood lumber: 144 cubic inches, or a 1" × 12" × 12" board. Enter your board dimensions to get board feet and total cost.
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How board feet work
Hardwood is sold by volume, not length, because boards come in random widths and lengths. One board foot = 144 cubic inches of wood.
Formula: thickness (in) × width (in) × length (ft) ÷ 12 = board feet
Hardwood thickness is quoted in "quarters" of an inch, based on the rough-sawn size before planing:
| Name | Rough thickness | Typical surfaced (S2S) |
|---|---|---|
| 4/4 ("four quarter") | 1" | 13/16" |
| 5/4 | 1¼" | 1-1/16" |
| 6/4 | 1½" | 1-5/16" |
| 8/4 | 2" | 1¾" |
| 12/4 | 3" | 2¾" |
Important: board feet are always calculated from the rough (nominal) thickness — a surfaced 4/4 board that now measures 13/16" is still billed as 1" thick.
Buying hardwood: quick tips
- Add 15–30% to your project's board-foot total for defects, grain matching and milling loss.
- Prices vary hugely by species: pine and poplar might be $3–4/bd ft, walnut $8–15/bd ft at a hardwood dealer.
- Softwood construction lumber (2×4s etc.) is sold per piece, not by the board foot — this unit is mainly for hardwood.
Frequently asked questions
How many board feet are in a 2x4?
An 8-foot 2×4 is nominally 5.33 board feet (2 × 4 × 8 ÷ 12). Note construction lumber is usually priced per piece, and its actual size is 1.5" × 3.5".
What does 4/4, 8/4 lumber mean?
Hardwood thickness is quoted in quarters of an inch, rough-sawn: 4/4 is 1 inch, 8/4 is 2 inches. After planing, a 4/4 board typically measures 13/16", but it's still billed as 1".
Is a board foot the same as a linear foot?
No. A linear foot is just length, ignoring width and thickness. A board foot is a volume: 1 inch thick × 12 inches wide × 12 inches long.
How do I estimate board feet for a project?
Total the board feet of every finished part, then add 15–30% waste depending on the wood grade and how much grain matching you plan to do.