How do you calculate board feet in a log?

Measure the small-end diameter inside bark (DIB) in inches and the log length in feet. Then apply a log rule formula (Doyle, Scribner, or International). If you want it fast, use our log calculator (https://board-foot-calculator.org/tools/log-calculator).

Which log rule is most accurate?

The International 1/4-Inch Rule is generally considered most accurate. Doyle often underestimates small logs, while Scribner is moderately accurate for many sizes.

What is the Doyle log rule?

Doyle is one of the oldest log rules (often dated to 1825). Formula: (D − 4)² × L ÷ 16. It tends to underestimate smaller logs.

What is DIB (diameter inside bark)?

DIB means Diameter Inside Bark: the diameter measured at the small end of the log, excluding bark thickness. It is the standard input for log rules.

Why does Doyle underestimate small logs?

Doyle subtracts 4 inches in the formula. That deduction is proportionally larger for small logs, so the estimate drops a lot when D is small.

What is overrun in log scaling?

Overrun is when actual lumber yield is higher than the log rule estimate. Doyle often shows high overrun on small logs because the rule is conservative.

Which log rule should I use?

Use the rule your market uses. Doyle is common in parts of the Southeast US; Scribner is common in the West; International is used when accuracy is the priority.

Can I calculate board feet for standing trees?

You can estimate, but it is less accurate. Standing trees use DBH and merchantable height with assumptions about taper. For single logs, our log calculator (https://board-foot-calculator.org/tools/log-calculator) is a better starting point.

How to Calculate Board Feet in Logs: Doyle, Scribner & International Rules

Last Updated: 2025-12-28

Learn how to calculate board feet in logs using Doyle, Scribner, and International rules. Compare accuracy, see formulas, and use our free log calculator.

Three log scaling rules estimate lumber yield differently. Here's how they compare.

Quick comparison of Doyle, Scribner, and International log rules.
Rule	Accuracy	Common region	Small logs	Large logs
Doyle	Low	Southeast US	Underestimates	More accurate
Scribner	Medium	West Coast	Slightly low	More accurate
International 1/4"	High	Modern standard	Accurate	Accurate

Calculate Log Board Feet → Board Foot Calculator

What is log scaling?

Log scaling is estimating how many board feet of lumber a round log can produce. Mills and buyers use it for pricing and inventory.

The two key measurements are the small-end diameter inside bark (DIB) and the log length. If you need the board foot definition first, see what is a board foot .

How to measure a log (DIB + length)

Measure the small-end diameter inside bark (DIB) in inches.
Measure log length in feet (common lengths are 8', 10', 12', 16').

Measure DIB at the small end (inside bark), then measure the log length.

Three rules explained (formulas)

We use D for DIB in inches and L for length in feet.

Doyle Rule

Oldest common rule. Often underestimates smaller logs.

BF = (D − 4)² × L ÷ 16

Scribner Rule (approx.)

Often used as a table. This page shows a common approximation.

BF = (0.79 × D² − 2 × D − 4) × L ÷ 16

International 1/4-Inch Rule

Generally the most accurate. The full polynomial is longer, so it's easiest to use the calculator.

BF = 0.04976191 × L × D²
   + 0.006220239 × L² × D
   − 0.1854762 × L × D
   + 0.000259176 × L³
   − 0.01159226 × L²
   + 0.04222222 × L

Example (D=12", L=16')

Same log, different rule → different estimate:

Example comparison for a single log across three rules.
Rule	Board feet (BF)
Doyle	64
Scribner	85.76
International	96.92

Overrun (why you may see more lumber than the estimate)

Overrun happens when the actual yield is higher than the rule estimate.

Overrun % = (Actual − Estimate) ÷ Estimate × 100%

Doyle often shows high overrun on small logs because the rule is conservative.

Quick reference (common sizes)

These are example estimates for common diameters and lengths. Use the calculator for any size.

Quick reference table of estimated board feet for common log sizes, shown for Doyle, Scribner, and International rules.
DIB (in)	Length (ft)	Doyle	Scribner	International
12"	8'	32	42.88	44.03
12"	16'	64	85.76	96.92
14"	8'	50	61.42	62.56
14"	16'	100	122.84	135.57
16"	8'	72	83.12	84.27
16"	16'	144	166.24	180.59
18"	8'	98	107.98	109.17
18"	16'	196	215.96	231.98
20"	8'	128	136	137.25
20"	16'	256	272	289.74

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