What is a board foot?

A board foot (BF) is a unit of lumber volume equal to a piece 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). Log rules estimate how many board feet of sawn lumber a log can yield.

Which log rule should I use?

Doyle is traditional in the eastern US but underestimates small logs. Scribner is common in the Pacific Northwest and is more accurate for larger logs. International 1/4-inch is generally the most accurate across all sizes and is preferred by many state agencies.

What diameter should I measure?

All three rules use the small-end diameter inside bark (DIB). Measure the narrowest end of the log after removing bark. If you only have outside bark (DOB) diameter, subtract twice the estimated bark thickness.

How is cubic-foot volume calculated?

Cubic-foot volume uses the formula for a cylinder: V = pi * r^2 * L, where r is the radius of the small-end diameter in feet and L is the log length in feet. This is a conservative estimate since logs are not perfect cylinders.

Why do the three rules give different results?

Each rule was developed at different times with different assumptions about saw kerf (the material lost during sawing), slab allowances, and log taper. Doyle assumes a 4-inch slab allowance regardless of log size, making it poorly suited for small logs.

What are the valid input ranges?

Diameter should be between 6 and 60 inches, and length should be between 8 and 40 feet for reliable results. All three rules are empirically derived and may produce unrealistic estimates outside these ranges.

Log Volume Calculator

Name: Log Volume Calculator
Availability: InStock
Author: Nham Vu

Enter log diameter and length to calculate board-foot volume using Doyle, Scribner, or International 1/4-inch log rules.

Log Measurements

Log Rule

Small-End Diameter (inside bark)

inches

Measure at the narrow (small) end, bark removed. Range: 6–60 in.

Log Length

feet

Standard log lengths: 8, 10, 12, 16, 20 ft. Range: 8–40 ft.

Rule Comparison

Log Rule	Board Feet	Cubic Feet

Board-foot volumes vary by rule; cubic-foot volume is rule-independent.

Enter log dimensions and click Calculate

Summary

Enter log diameter and length to calculate board-foot volume using Doyle, Scribner, or International 1/4-inch log rules.

How it works

Select the log rule you want to use (Doyle, Scribner, or International 1/4-inch).
Enter the small-end diameter inside bark (DIB) in inches.
Enter the log length in feet.
Click Calculate to see board-foot volume, cubic-foot volume, and a per-rule comparison.
Use the comparison table to view all three rules side-by-side for the same log.

Use cases

Estimating timber value when buying or selling logs at a sawmill.
Scaling logs in the field for accurate load tallies.
Comparing log rules to understand yield differences between buyers and sellers.
Teaching forestry students the mathematics behind board-foot log rules.
Quick volume checks for timber cruising and harvest planning.
Determining cubic-foot volume for pulpwood or biomass pricing.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu