Board Foot Calculator
Board Foot Calculator
Calculate board feet for lumber and woodworking projects
What is a Board Foot?
A board foot is a unit of volume for measuring lumber in the United States and Canada. One board foot is equivalent to a piece of wood measuring 1 foot × 1 foot × 1 inch (12" × 12" × 1"). It represents 144 cubic inches of wood, regardless of the shape or dimensions of the piece.
How to Calculate Board Feet
The formula for calculating board feet is:
Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12
Note that the length is measured in feet, while thickness and width are measured in inches. If you have the length in inches, you'll need to divide it by 12 first to convert to feet.
Understanding Lumber Dimensions
Nominal vs. Actual Dimensions
In lumber terminology, there's an important distinction between "nominal" and "actual" dimensions:
- Nominal dimensions are what the lumber is called or labeled as in stores (e.g., 2×4, 1×6).
- Actual dimensions are the true measurements after the lumber has been surfaced (planed smooth). These are typically smaller than the nominal dimensions.
Common Nominal vs. Actual Dimensions:
- 1×4: Actually measures approximately 3/4" × 3-1/2"
- 1×6: Actually measures approximately 3/4" × 5-1/2"
- 1×8: Actually measures approximately 3/4" × 7-1/4"
- 2×4: Actually measures approximately 1-1/2" × 3-1/2"
- 2×6: Actually measures approximately 1-1/2" × 5-1/2"
- 2×8: Actually measures approximately 1-1/2" × 7-1/4"
- 4×4: Actually measures approximately 3-1/2" × 3-1/2"
Uses for Board Foot Calculations
- Estimating the amount of lumber needed for a project
- Calculating the cost of lumber (often priced per board foot)
- Determining shipping weight and volume
- Planning for wood storage space
- Comparing prices between different lumber suppliers
- Estimating the yield from logs or rough lumber
Tips for Using the Calculator
- Always use actual dimensions for accurate calculations
- For multiple pieces of the same size, use the quantity field
- When planning a project, add 10-15% extra for waste and mistakes
- For rough lumber, use the actual measured dimensions
- Remember that exotic or specialty woods are often more expensive per board foot
- Use the total cost calculator to estimate your project budget
Common Lumber Grades
Lumber is graded based on appearance and structural characteristics:
Hardwood Grades
- FAS (First and Second) - Highest grade with minimal defects
- Select - High quality with slightly more defects than FAS
- No. 1 Common - Good quality with some defects
- No. 2 Common - More defects, but still usable for many projects
Softwood Grades
- Clear - Minimal knots and defects
- Select - Small, tight knots allowed
- No. 1 - Standard construction grade
- No. 2 - Economy grade with more knots
- No. 3 - Utility grade with significant defects