Board Foot Calculator
Lumber volume measurement tool
Calculate board feet from lumber dimensions. A board foot is a unit of volume equal to a 1-inch thick board that is 1 foot wide and 1 foot long (144 cubic inches).
Lumber Dimensions
Board Foot Formula
BF = (Thickness × Width × Length) ÷ 12
Where thickness and width are in inches, and length is in feet. One board foot = 144 cubic inches.
Common Lumber Sizes — Board Feet per Foot of Length
| Nominal Size | Actual Size | BF / ft |
|---|---|---|
| 1×4 | 3/4" × 3-1/2" | 0.33 |
| 1×6 | 3/4" × 5-1/2" | 0.50 |
| 1×8 | 3/4" × 7-1/4" | 0.67 |
| 1×12 | 3/4" × 11-1/4" | 1.00 |
| 2×4 | 1-1/2" × 3-1/2" | 0.67 |
| 2×6 | 1-1/2" × 5-1/2" | 1.00 |
| 2×8 | 1-1/2" × 7-1/4" | 1.33 |
| 2×10 | 1-1/2" × 9-1/4" | 1.67 |
| 2×12 | 1-1/2" × 11-1/4" | 2.00 |
| 4×4 | 3-1/2" × 3-1/2" | 1.33 |
Frequently Asked Questions
Understanding Board Feet: The Complete Guide
The board foot is the standard unit of measure for hardwood lumber in the United States and Canada. Whether you're buying wood from a lumberyard, pricing a woodworking project, or estimating materials for a construction job, understanding board feet is essential.
What Exactly Is a Board Foot?
A board foot represents a volume of wood equal to 144 cubic inches — equivalent to a piece 1 inch thick, 12 inches wide, and 12 inches long. Unlike square footage (which only measures area) or linear footage (which only measures length), board feet capture the full three-dimensional volume of a piece of lumber.
This matters because hardwood lumber comes in varying thicknesses. A 2-inch-thick board contains twice the wood of a 1-inch board with the same width and length, and the board foot measurement reflects that difference.
How Hardwood Lumber Is Sold
Hardwood dealers price lumber by the board foot. When you walk into a hardwood dealer and see "Walnut 8/4 — $14.50/BF," that means each board foot of 2-inch-thick walnut costs $14.50.
Common rough thickness designations:
- 4/4 (four-quarter): 1 inch thick
- 5/4 (five-quarter): 1.25 inches thick
- 6/4 (six-quarter): 1.5 inches thick
- 8/4 (eight-quarter): 2 inches thick
- 12/4 (twelve-quarter): 3 inches thick
- 16/4 (sixteen-quarter): 4 inches thick
Board Feet vs. Linear Feet vs. Square Feet
| Unit | Measures | Used For | |------|----------|----------| | Board Foot | Volume (3D) | Hardwood lumber pricing | | Linear Foot | Length only | Moldings, trim, dimensional lumber | | Square Foot | Area (2D) | Flooring, paneling, sheet goods |
Tips for Accurate Estimates
- Always add a waste factor. For typical projects, add 15–20% to your calculated board feet to account for defects, saw kerf, and mistakes.
- Measure rough dimensions when buying rough lumber. After planing, you'll lose approximately 1/8" to 3/16" per surfaced face.
- Round up when ordering. Lumber yards sell full boards, so round your total up to the nearest whole board.
Board Foot Pricing by Species
Lumber prices vary dramatically by species. Here are typical ranges for kiln-dried 4/4 stock:
- Construction softwoods (pine, spruce): $2–5/BF
- Common domestic hardwoods (red oak, poplar, soft maple): $4–8/BF
- Premium domestic hardwoods (walnut, cherry, white oak): $8–16/BF
- Exotic species (purpleheart, padauk, wenge): $12–30/BF
- Rare exotics (cocobolo, ebony, figured maple): $30–100+/BF