Doyle, Scribner, and International
Three log rules, one log. The buyer and the seller have to name which rule the price uses.
Same log, three scales
A log rule estimates the board feet a saw will get from a log. Doyle, Scribner, and International answer that question with different allowances for slab and sawdust, so the same stick produces three numbers. The price has to name the rule. Averaging them does not produce a fourth official scale.
Doyle is a formula: diameter minus 4, squared, times length in feet, divided by 16. Scribner Decimal C is a table. International 1/4 inch is a formula that this site rounds to the nearest 5 board feet, while the unrounded value stays visible.
A 16 inch by 16 foot log is 144 board feet by Doyle, 160 by Scribner Decimal C, and 180 by International 1/4 inch. The International formula before rounding is 180.6.
On that 16 inch log the three scales sit close together. On a smaller log, Doyle drops faster because of the 4 inch allowance. On a larger log, Doyle can run ahead of the Scribner table. Read the rule your buyer uses, then enter that diameter and length on the log board foot calculator.
After the log is sawn
A log scale is not the board-foot tally of the boards you stack. Once the lumber is sawn, measure thickness, width, and length on the board foot calculator. Hardwood thickness in quarters is a separate step, covered in 4/4 and 8/4.
This guide explains the measurement the calculators use. It is not a permit review.
Use it on a calculator
FAQ
What is the Doyle formula?
Doyle board feet are the diameter in inches minus 4, squared, times the length in feet, divided by 16. A result below zero stays at zero. The subtracted 4 inches is why Doyle falls behind the other rules on a small log: a larger share of the diameter is treated as waste. On a large log the same formula can run ahead of Scribner. Use the rule the sale names, and do not average the three answers.
Why is Scribner a table?
Scribner Decimal C is a published table of board feet by diameter and length. The calculator uses that table when the diameter and length hit it. When they do not, it falls back to the Bruce and Schumacher formula and says so on the result. The diameter is rounded to the nearest inch before the lookup. The table value is the scale, not a second formula you should mix with Doyle.
How does International rounding work?
The International 1/4 inch scale on this site uses the Grosenbaugh form. The page shows the unrounded formula to a tenth of a board foot, then rounds the scale to the nearest 5 board feet. A formula of 180.6 becomes 180. That rounded number is the scale you compare with Doyle and Scribner. The tenth stays on screen so you can see what the rounding did.
By Lumber Calc Editorial Team . The numbers follow the rules on the linked calculator pages. Last updated Oct 24, 2026.