Board Foot Calculator
Calculate board feet from the thickness, width and length of lumber, for one board or a whole order, and estimate the cost at a price per board foot.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Total board feet
- 40 bd ft
- 10 pieces of 1 in x 6 in x 8 ft
- Board feet per piece
- 4 bd ft
- 576 cubic inches
- Total length
- 80 ft
Board Foot formula
Board feet per piece = Thickness (in) x Width (in) x Length (ft) / 12
Total board feet = Board feet per piece x Number of pieces
Cost = Total board feet x Price per board footWorked example
Six pieces of 2 x 10 lumber 12 ft long, priced by the board foot at $4.00: 2 x 10 x 12 / 12 = 20 board feet each, so 120 board feet total and a cost of $480. If the yard measures actual dimensions instead (1.5 x 9.25 in), the same boards are 13.9 board feet each.
Quick reference
| Nominal size | Board feet per 8 ft piece |
|---|---|
| 1 x 4 | 2.67 |
| 1 x 6 | 4.00 |
| 1 x 8 | 5.33 |
| 1 x 12 | 8.00 |
| 2 x 4 | 5.33 |
| 2 x 6 | 8.00 |
| 2 x 8 | 10.67 |
| 2 x 12 | 16.00 |
How to calculate board feet
A board foot is a volume, not a length: 12 x 12 x 1 inches. Multiply thickness and width in inches by length in feet and divide by 12. If all three dimensions are in inches, divide by 144 instead. The formula works for any size, so a wide slab and a stack of thin boards are compared on the same basis.
For hardwood, use the nominal (rough-sawn) thickness even if the board has been planed. A 4/4 board surfaced to 13/16 in is still sold as 1 in thick. Width is measured at the narrowest point of the board, and length is rounded down to the nearest foot at most yards.
Board feet vs linear feet
Construction lumber (2x4, 2x6) is priced per piece or per linear foot because the sizes are standard. Hardwood comes in random widths and lengths, so it is priced per board foot to make different boards comparable. When quoting a project, convert your cut list to board feet and add 15 to 30 percent for defects, grain matching and cutoffs.
Key facts
- One board foot is 144 cubic inches of wood: a piece 1 in thick, 12 in wide and 12 in long.
- Hardwood thickness is quoted in quarters of an inch: 4/4 is 1 in, 6/4 is 1.5 in, 8/4 is 2 in.
- A 2 x 4 that is 8 ft long is 5.33 board feet by nominal size, even though its actual size is 1.5 x 3.5 in.
- Hardwood lumber is sold rough by nominal thickness; surfacing removes about 1/4 in but you still pay for the rough size.
- 1,000 board feet is written as 1 MBF; large orders and sawmill prices are quoted per MBF.
Frequently asked questions
How many board feet are in a 2x4x8?
5.33 board feet using nominal dimensions (2 x 4 x 8 / 12). Using actual dimensions of 1.5 x 3.5 in it would be 3.5, but lumber is always figured at nominal size.
How many board feet in a 1x6x8?
4 board feet: 1 x 6 x 8 divided by 12.
What does 4/4 mean in hardwood?
Four quarters of an inch, or 1 in nominal thickness. 5/4 is 1.25 in, 6/4 is 1.5 in and 8/4 is 2 in. The fraction refers to the rough-sawn thickness before planing.
How do I convert board feet to cubic feet?
Divide by 12. One cubic foot of wood is 12 board feet.
Sources and references
- Forest Products Terminology fact sheet F-85 (Ohio State University Extension)
- Hardwood Lumber Grades, FNR-130 (Purdue Extension)
- NHLA Rules for the Measurement and Inspection of Hardwood and Cypress (National Hardwood Lumber Association)
Next steps for this project
The usual order for a framing, decks & fences project. See all framing, decks & fences calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.