International 1/4-Inch Log Rule Calculator (Clark Version)

Spike VM

The International 1/4-Inch Log Rule (Clark Version) calculates the estimated board feet in a single log based on its small-end diameter (DIB) and length. This calculator applies Clark's exact polynomial formulas for standard log lengths (4, 8, 12, 16, and 20 feet) and provides a live board foot result with session history and CSV export functionality.

Log Length (ft): must be one of the following: 4, 8, 12, 16, or 20 feet

Related Forestry Calculators:

International 1/4-Inch Log Rule Calculator (Clark Version)

ft

inch
Diameter Measured Inside Bark = DIB


bf

Calculation History

Total Board Feet: 0 bf

Calculator

  1. Length (ft): choose the log length
  2. the small-end diameter measured inside the bark in inches

Results

  1. the board foot estimate of the logs
  2. Running Total: automatically sums all entries.
  3. Add more logs and use Copy or Download CSV to save your data.
  4. Use Clear History to reset the calculation log and the running total.


Clark's International 1/4-Inch Log Rule Formulas

Each length uses a specific polynomial equation:

  • 4 ft: \( BF = 0.199D^2 - 0.642D \)
  • 8 ft: \( BF = 0.398D^2 - 1.086D - 0.271 \)
  • 12 ft: \( BF = 0.597D^2 - 1.330D - 0.715 \)
  • 16 ft: \( BF = 0.796D^2 - 1.375D - 1.230 \)
  • 20 ft: \( BF = 0.995D^2 - 1.221D - 1.719 \)

Example Calculation (16 ft log with 14 in DIB)

\[ \begin{align*} BF &= 0.796 \cdot 14^2 - 1.375 \cdot 14 - 1.230 \\ &= 0.796 \cdot 196 - 19.25 - 1.230 \\ &= 156.016 - 19.25 - 1.230 \\ &= 135.54 \end{align*} \]

Conversions:

one board foot (bf) = 0.0833333333333333 cubic feet (ft³)
one board foot (bf) = 0.002359737216 cubic metres (m³)

Board Foot Log Rule Calculators

If you have any questions or comments please Contact Us
Privacy Policy
© 1998, VmNet.