Log Board Foot Calculator
Estimate the lumber yield of a log in board feet using standard log scaling rules. Enter the small-end diameter and length to calculate under three log rules.
Result
288 board ft
Estimated log scale is 288 board ft, or 144 board feet per log.
Quick Answer
A log board foot calculator estimates lumber volume using a log scaling rule. The Doyle rule formula is: Board Feet = ((Diameter − 4)² / 16) × Length. For a 12-inch diameter log, 16 feet long: ((12 − 4)² / 16) × 16 = (64/16) × 16 = 64 board feet. The Scribner and International rules give different results for the same log -- this calculator shows all three for comparison.
Log Board Foot Calculator Explained: What It Measures
A board foot is 144 cubic inches of sawn lumber. Log scaling rules (Doyle, Scribner, International 1/4-inch) estimate sawn board foot yield from small-end diameter and length.
The Log Board Foot Scaling Formulas And How They Work
Doyle Rule: BF = ((D − 4)² / 16) × L Scribner Rule: BF ≈ (0.79 D² − 2D − 4) × L / 16 International 1/4": BF ≈ (0.22 D² − 0.71 D) × L
- Doyle: ((D − 4)² / 16) × L
- Scribner: (0.79 D² − 2D − 4) × L / 16
- International 1/4": (0.22 D² − 0.71 D) × L
- D: small-end inside-bark diameter in inches
How To Use The Log Board Foot Calculator In 4 Steps
Inputs
- Small-End Diameter: inside-bark diameter in inches at narrow end
- Log Length: length in feet
- Log Rule: Doyle, Scribner, or International 1/4-inch
Steps
- Measure small-end inside-bark log diameter in inches.
- Measure log length in feet.
- Select log scaling rule.
- Read estimated board-foot yield.
Log Board Foot Scaling Rule Example, Worked In Full
White oak log with 14-inch small-end diameter and 12-foot length.
- Doyle: ((14 − 4)² / 16) × 12 = (100 / 16) × 12 = 75 BF.
- Scribner: (0.79 × 196 − 28 − 4) × 12 / 16 = 92.1 BF.
Yield is 75 board feet on Doyle scale; 92.1 board feet on Scribner scale.
When A Log Board Foot Calculator Gives The Right Answer
Use this calculator for timber cruise estimates, buying/selling log comparisons, or evaluating sawmill timber contracts.
Assumptions
- Diameter measured inside-bark at small end.
- Logs assumed sound without rot/crook defect deductions.
Limitations
- Estimates sawn lumber volume only; does not calculate log weight or chip volume.
- Does not apply cull deductions for defect logs.
In Practice
The Doyle rule consistently underestimates yield for small-diameter logs (below 16 inches) and overestimates for very large logs (above 28 inches). Always confirm which rule your buyer or seller uses before negotiating price per MBF.
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Frequently Asked Questions: Log Board Foot Scaling
What is a board foot and how is it different from a linear foot?
A board foot is a 144 cubic inch volume (1 ft × 1 ft × 1 in). Linear feet measure length only.
Why do the three log rules give different estimates for the same log?
Different rules use different historical assumptions for kerf width, slab loss, and log taper.
Which log rule should I use?
Use the rule specified in your local market contract (Doyle in US South; Scribner in US Northwest).
What is MBF in lumber pricing?
MBF stands for thousand board feet ($/MBF × BF / 1,000 = total dollar value).
Is this the same as the log weight calculator?
No. Board feet measures sawn lumber volume; log weight measures physical green mass.
Sources
Last updated: . Reviewed for accuracy against the formula shown above.