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Board Feet Calculator
Free tool to calculate board feet (BF) for hardwood, softwood, and dimensional lumber. Supports 4/4, 5/4, 6/4, 8/4 thickness and per-board-foot cost.
Board feet
4.00 BF
Total cost
$0.00
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Open OptiSaw — Free Cut List Optimizer →How board feet are calculated
A board foot (BF) is a unit of lumber volume equal to 144 cubic inches. The standard formula uses thickness in inches, width in inches, and length in feet:
Or, if your length is in inches:
For multiple pieces, multiply the result by the quantity.
Quarter-thickness (4/4) lumber explained
Hardwood lumber is sold in quarter-inch increments. The notation "4/4" means four quarters of an inch, or one full inch nominal thickness.
| Notation | Nominal thickness | Typical surfaced (S2S) |
|---|---|---|
| 4/4 | 1″ | 13/16″ |
| 5/4 | 1¼″ | 1-1/16″ |
| 6/4 | 1½″ | 1-5/16″ |
| 8/4 | 2″ | 1¾″ |
| 12/4 | 3″ | 2¾″ |
| 16/4 | 4″ | 3¾″ |
Common board foot examples
| Lumber | Calculation | Board feet |
|---|---|---|
| 1×6 × 8 ft | 1 × 6 × 8 ÷ 12 | 4.00 BF |
| 2×4 × 8 ft | 2 × 4 × 8 ÷ 12 | 5.33 BF |
| 2×6 × 10 ft | 2 × 6 × 10 ÷ 12 | 10.00 BF |
| 2×8 × 12 ft | 2 × 8 × 12 ÷ 12 | 16.00 BF |
| 4/4 × 8″ × 6 ft (oak) | 1 × 8 × 6 ÷ 12 | 4.00 BF |
| 8/4 × 6″ × 8 ft (walnut) | 2 × 6 × 8 ÷ 12 | 8.00 BF |
Frequently asked questions
What is a board foot?
A board foot (BF) is a unit of lumber volume equal to 144 cubic inches — for example, a piece 1″ thick × 12″ wide × 12″ long. Hardwood is sold by the board foot in most of the US and Canada.
How do you calculate board feet?
Multiply thickness (in inches) × width (in inches) × length (in feet), then divide by 12. Or: thickness × width × length all in inches, divided by 144.
What does 4/4 lumber mean?
Hardwood is graded in quarter-inch increments. 4/4 ("four quarter") means nominal one-inch thickness, 5/4 means 1¼″, 6/4 means 1½″, 8/4 means 2″.
How much does board foot lumber cost?
Hardwood lumber typically ranges from $4–$15 per board foot depending on species. Poplar is the cheapest hardwood, walnut and white oak are mid-range, and exotic species can cost much more.
Is OptiSaw a free alternative to paid lumber calculators?
Yes. OptiSaw is a free, no-sign-up alternative to Cutlist Optimizer Pro, MaxCut, and SketchList. It runs entirely in your browser, supports both 2D sheet goods and 1D lumber optimization, and exports printable PDF cut plans.