Log Volume Calculator (Doyle, Scribner, International ¼″ & Cubic)

How it works

Doyle: bf = (D − 4)² × L ÷ 16. Scribner: bf ≈ (0.79 D² − 2D − 4) × L ÷ 16. International ¼″: bf = Σ 4-ft sections (0.22 D² − 0.71 D) × 0.905, with D increasing 0.5″ per section. Smalian cubic: V = (A_small + A_large) ÷ 2 × L

Log rules estimate how many board feet of lumber a log will yield, and three rivals have survived a century of argument. Doyle, the simplest, subtracts four inches from the diameter for slabs and squares the rest — harshly penalising small logs (a 10-inch log scales at half its real yield) and slightly over-scaling big ones, which is why buyers in the South like it. Scribner came from diagrams of boards drawn inside circles and is the US Forest Service standard in the West. The International ¼-inch rule accounts for a quarter-inch kerf and half an inch of taper every four feet and tracks modern sawmill output best. Because they differ by 20–50% on small logs, the rule named in a timber contract matters as much as the price. Cubic volume, used everywhere outside North America, avoids the argument.

Worked example

A 16″ small-end, 12 ft log: Doyle 108 bf, Scribner 125 bf, International ¼″ 131 bf; about 18 ft³ of solid wood (0.52 m³). At $450 per MBF the same log is worth $49 by Doyle and $59 by International.

Frequently asked questions