Cubic Log Volume

Cubic foot volume is calculated as the frustum of a geometric shape.

Frustum of a paraboloid or Smalain's Formula

frustum of a paraboloid.
Figure 1. A frustum of a paraboloid or often call the Smalian's Formula.

$$V = \frac{L}{2} \left( As + Al \right)$$

where V is the cubic Volume in the dimensions of L3, As is the area of the small end in dimensions of L2, Al is the area of the large end in dimensions of L2. Note the diameter of the ends are ususally no measured in the same units as L so the units must be converted.

Frustum of a cone.

Frustum of a cone.
Figure 2. A frustum of a cone.

$$V = \frac{L}{3} \left( As + \sqrt{As Al} + Al \right)$$

where V is the cubic Volume in the dimensions of L3, As is the area of the small end in dimensions of L2, Al is the area of the large end in dimensions of L2. Note the diameter of the ends are ususally no measured in the same units as L so the units must be converted.

Frustum of a neiloid

frustrum of a neiloid.
Figure 3. A frustum of a neiloid.

$$V = \frac{L}{4} \left( As + \sqrt[3]{As^2 Al} + \sqrt[3]{As Al^2} + Al \right)$$

where V is the cubic Volume in the dimensions of L3, As is the area of the small end in dimensions of L2, Al is the area of the large end in dimensions of L2. Note the diameter of the ends are ususally no measured in the same units as L so the units must be converted.

Example

Imperial Units
dia small = 10 in inches
dia large = 12 in inches
L = 16 feet
unittype = "imperial"
Answer (smalian) = 10.647 cubic feet
Answer (cone) = 10.588 cubic feet
Answer (neiloid) = 10.568 cubic feet

Metric Units
dia small = 25 in centimeters
dia small = 29 in centimeters
L = 5 in meters
unittype = "metric"
Answer (smalian) = 0.287848 cubic meters
Answer (cone) = 0.286801 cubic meters
Answer (neiloid) = 0.286452 cubic meters

Code

Excel® Visual Basic Code

R Statistical Package Code (Cone)
R Statistical Package Code (Smalian)
R Statistical Package Code (Neiloid)

Python Code (Cone)
Python Package Code (Smalian)
Python Code (Neiloid)

Go Code

C Code


Creative Commons License
Forestry Functions by David R. Larsen is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Author: Dr. David R. Larsen, Copyright 2012
Created: November 1, 2012
Last Updated: January 5, 2020