About this Board Foot (Lumber)
Hardwood lumber is typically sold by volume (Board Feet) rather than linear length. This ensures you pay for the total amount of wood fiber you receive, regardless of board dimensions. A 'Board Foot' represents a volume of 144 cubic inches (12" x 12" x 1").
Who this calculator is for
- Woodworkers pricing rough lumber orders from a yard or sawmill.
- Carpenters comparing the volume of boards with different widths and thicknesses.
- Furniture makers estimating how much hardwood stock a project will require.
When to use it
- Convert board dimensions into total board feet before ordering lumber.
- Estimate material cost when a species is priced per board foot.
- Compare multiple board sizes or quantities on the same project plan.
How to use this calculator
- Enter the Thickness (in inches).
- Enter the Width (in inches).
- Enter the Length (in feet).
- Enter the Quantity of boards.
- The result is total Board Feet (FBM).
Key assumptions
- Thickness and width are entered in inches, while length is entered in feet.
- All entered dimensions and quantity should be positive numbers.
- The calculation gives gross lumber volume and does not deduct defects, kerf loss, or milling waste.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
Board Feet = (Thickness in inches × Width in inches × Length in FEET) / 12
Alternatively, if all dimensions are in inches: (T × W × L) / 144.
Inputs explained
Thickness
Often referred to in quarters (e.g. 4/4 = 1 inch, 8/4 = 2 inches).
Length
Note that lumber length is typically measured in feet, while width/thickness are in inches.
Understanding your results
Use the Total Board Feet to estimate cost. If Walnut is $10/bd ft and you have 20 bd ft, the cost is $200.
Example scenarios
Standard Board
1 in thick, 6 in wide, 8 ft long. (1 * 6 * 8) / 12 = 4 Board Feet.
Thick Slab
2 in thick, 10 in wide, 6 ft long. (2 * 10 * 6) / 12 = 10 Board Feet.
Key Features
- Standard Industry Formula
- Bulk Quantity Support
- Cost Estimation Helper
Tips & Best Practices
- Lumber yards often round up dimensions.
- Rough sawn lumber is thicker than surfaced lumber (S4S), but is usually sold based on its rough thickness.
Glossary of Terms
- FBM
- Foot Board Measure. Another abbreviation for Board Foot.
- Linear Foot
- A measure of length only, ignoring width and thickness.
- 4/4, 5/4, 8/4
- Standard terminology for rough lumber thickness in quarter-inches.