Log Board Foot Calculation

Log Board Foot Calculation (Doyle Rule):

Measure the Diameter:Measure the log's small-end diameter inside the bark (in inches). This is often abbreviated as DIB (Diameter Inside Bark).

Ensure the measurement is taken at the narrowest point of the log.

Measure the Length:

Measure the log's length in feet.

Apply the Doyle Formula:

Board Feet (BF)

=

(

Diameter

−

4

4

)

2

×

Length

Board Feet (BF)=(

4

Diameter−4

​

 )

2

 ×Length

Subtract 4 inches from the diameter.

Divide the result by 4, then square it.

Multiply by the log length.

Example Calculation:

Suppose you have a log with:

Diameter (DIB) = 20 inches

Length = 16 feet

Subtract 4 from the diameter:

20

−

4

=

16

20−4=16

Divide by 4:

16

4

=

4

4

16

​

 =4

Square the result:

4

2

=

16

4

2

 =16

Multiply by the length:

16

×

16

=

256

Board Feet (BF)

16×16=256Board Feet (BF)

Other Log Scales:

Scribner Rule: More accurate for small logs.

International 1/4-Inch Rule: Accounts for sawmill kerf and provides more accurate estimates.

Online Calculators:

If you'd prefer a faster way, use an online log board foot calculator. Simply input the diameter and length, and it computes the board feet for you.