International ¼″ Log Rule – the most accurate board foot rule

It allows for a ¼-inch kerf, shrinkage and log taper, so it comes closest to the real lumber yield.

What is the International ¼″ Log Rule?

The International ¼-inch log rule is a formula for log volume in board feet that allows for a ¼-inch saw kerf, lumber shrinkage and a taper of ½ inch per 4 feet. Of the US log rules, it comes closest to the actual lumber yield.

Formula

BF = 0.04976191·L·D² + 0.006220239·L²·D − 0.1854762·L·D + 0.0002591767·L³ − 0.01159226·L² + 0.04222222·L

D = small-end diameter in inches · L = length in feet. This is the continuous form of the rule (Grosenbaugh); the official table rounds the result to the nearest 5 board feet.

Worked example

A log 16 inches at the small end and 16 feet long: the formula gives 180.6 BF, the table rounded to 5 BF lists 180 BF.

Where it is used

The north-eastern United States, several state agencies and the Forest Service in the East, research and forestry schools.

Doyle vs Scribner vs International ¼″ ›

Frequently asked questions

Why is International ¼″ more accurate than Doyle?

It accounts for the real kerf, shrinkage and taper. Doyle deducts a fixed 4 inches, which badly distorts the result on small logs.

What does ¼ inch in the name mean?

The saw kerf width. There is also a ⅛-inch version, which gives higher numbers.

Is the result rounded?

The official table is – to 5 board feet. The calculator shows both the exact formula value and the rounded value.

Other log scaling methods

All 22 methods in the app ›

In your countryDoyle vs Scribner vs International ¼″Three US board foot rules, three different results for the same log. Clearly laid out, in numbers, with the reasons.BF · US · CA In your countrySmalian formulaWhen you cannot reach the middle of the log – on a deck or a truck – you measure both ends.m³ · US · CA In your countryDoyle Log RuleThe oldest log rule still in wide use in the southern and midwestern United States.BF · US In your countryScribner Decimal CA rule built by drawing boards into circles, today the standard for softwood logs in the western United States.BF · US · CA Huber formulaThe most widely used scaling method in Central Europe: one diameter at mid-length and the length.m³ · SK · CZ · DE · AT · FR · IE JAS (Japanese standard)The small-end diameter squared method, the standard for logs traded to Japan.m³ · JP Swedish scaling (toppmätning)Swedish sawmills pay by the small-end diameter: m³to is a cylinder from the top end.m³ · SE Hoppus formulaA traditional British rule still used in the tropical hardwood and teak trade.m³ · GB · IE · IN · GH · MY More methodsSTN 48 0009, ČSN 48 0009, Vermont, Universal (Daniels), Newton, GOST 2708-75, Brereton, Ontario Board Foot, Ontario Cubic, Roy, Alberta, BC Firmwood, Mid-girth, Guo Biao (GB/T 4814)All 22 methods ›