Lumber Calculator: Board Feet
Board feet is the standard unit for measuring and pricing hardwood lumber in the United States. Unlike linear feet (which only measures length) or square feet (which only measures area), board feet accounts for all three dimensions: thickness, width, and length. This makes it the right unit for comparing prices across different board sizes and for calculating the total wood volume in a project. The formula is straightforward: multiply the thickness in inches by the width in inches by the length in feet, then divide by 12. This calculator handles one board size at a time and multiplies by the number of boards to give you the total board feet for an order. It also accepts a price per board foot so you can estimate total material cost. Enter your board dimensions using actual (not nominal) measurements for the most accurate result. For construction lumber, nominal dimensions (what you ask for at the store) are commonly used in planning, and the calculator works with either. When buying hardwood from a specialty dealer, boards are often sold in random widths and lengths; use the actual measured dimensions for each board and enter boards one size at a time. Add 10 to 15% to your total board feet estimate to allow for waste from cutting, planing, and defect removal.
Board feet formula
Board feet per board = Thickness (in) x Width (in) x Length (ft) / 12
Total board feet = Board feet per board x Number of boards
Cost = Total board feet x Price per board foot
Worked example: 10 boards, 1 in x 6 in x 8 ft
- Board feet per board: 1 x 6 x 8 / 12 = 4.00 BF
- Total: 4.00 x 10 = 40.00 BF
- At $4.50/BF: 40.00 x $4.50 = $180.00
Common nominal vs actual lumber dimensions
| Nominal size | Actual size (inches) |
|---|---|
| 1x4 | 0.75 x 3.5 |
| 1x6 | 0.75 x 5.5 |
| 2x4 | 1.5 x 3.5 |
| 2x6 | 1.5 x 5.5 |
| 2x8 | 1.5 x 7.25 |
| 4x4 | 3.5 x 3.5 |
Lumber calculator: frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to a piece of wood 1 inch thick, 12 inches wide, and 12 inches long, which equals 144 cubic inches. It is the standard unit for pricing and selling hardwood lumber in the United States. Softwood lumber (used in construction framing) is sometimes sold by the linear foot or piece instead, but board feet is still commonly used for project planning.
How do I calculate board feet?
Board feet = Thickness (inches) x Width (inches) x Length (feet) / 12. For example, a board that is 1 inch thick, 6 inches wide, and 8 feet long contains 1 x 6 x 8 / 12 = 4 board feet. If you have multiple boards of the same size, multiply the board feet per board by the number of boards to get the total.
Do lumber dimensions mean what they say?
No. Nominal lumber dimensions (the name used at the lumber yard) are larger than actual dimensions. A 2x4 is actually 1.5 inches x 3.5 inches when dried and planed. A 1x6 is actually 0.75 inches x 5.5 inches. For board foot calculations using construction lumber, use the nominal dimensions unless you need precise volume. For hardwood, use the actual measured thickness and width.
Is board feet the same as square feet?
No. Square feet measures area (two dimensions). Board feet measures volume (three dimensions including thickness). A 1-inch-thick board has the same square footage as a 2-inch-thick board of the same length and width, but the 2-inch board has twice as many board feet. When buying hardwood, you pay per board foot, not per square foot.
How much does lumber cost per board foot?
Softwood construction lumber (pine, fir, SPF) typically costs $1 to $3 per board foot, though prices vary significantly with market conditions. Hardwood lumber ranges from about $3 per board foot for common species like poplar and oak to $20 or more per board foot for figured or exotic species. Check with your local lumber yard or home improvement store for current pricing.
Sources
- National Hardwood Lumber Association grading rules: nhla.com.
- American Softwood Lumber Standard PS 20: nist.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. Prices vary by species, grade, and market.