The International 1/4 volume of a tree in board feet is calculated based on the number of 16-foot sawlogs, or portions there off, the tree contains in merchantable lumber. The diameter of the tree is measured at breast height(DBH 4½ feet above the ground).

Examples:

tree height = 33 feet to a top diameter of 8 inches
33 ÷ 16 = 2 full 16 foot sections. Trim allowance would make up the rest.
Enter a 2 in the number of 16 foot sawlogs field of the calculator.

tree height of 16.5 feet
include a trim allowance and you would end up with a 16-foot sawlog.
Enter 1 in the number of 16 foot sawlogs field of the calculator.

tree height of 12.5 feet
include a trim allowance and you would end up with one 12 foot section. Enter 0.75 in the number of 16 foot sawlogs field of the calculator.

Wiant's International 1/4 Formula:

V = (1.52968L² + 9.58615L - 13.35212)+ (1.79620 - 0.27465L² - 2.59995L)d + (0.04482 - 0.00961L² + 0.45997²)d² where V = volume in mbf
d = diameter measured at breast height in inches
L = number of 16 foot saw logs

Calculation

1. the number of 16 foot sawlogs in the tree stem or part thereof (see table)
2. diameter of a tree measured at breast height

Result

1. board foot volume of the tree based on the Scribner log scale table for standing tree volumes.