Sawmill Yield Calculator

Each rule encodes a different assumption about sawing waste. University extension forestry publications, such as the University of Missouri's "How to Measure Trees and Logs," identify the Doyle and International 1/4" rules as the two most commonly used log-scaling methods in practice today, which is why this calculator leads with Doyle Rule BF as its highlighted output. Doyle assumes a generous slabbing allowance that overstates waste on small and mid-size logs, so it reads lowest there -- but because Doyle's (D-4)^2 term grows faster than Scribner's formula, Doyle crosses above Scribner at roughly 25 inches of small-end diameter and reads highest on large logs. International 1/4" assumes a thinner modern saw kerf and reads highest across most of the range up to that crossover. None of the three is "wrong" -- they're different conventions, and a buyer and seller need to agree which one a price is quoted against before comparing numbers.

No. All three rules -- Doyle, Scribner, and International -- compute board feet directly from Small-End Diameter and Log Length only; Taper never enters those formulas. Taper only affects the calculator's Large-End Diameter estimate and the rough Est. Recovery Rate figure, which compares the Doyle board-foot count against an estimated gross cylindrical volume that does grow with taper.

Diameter, by a wide margin. Because Doyle's formula squares the diameter term (D-4)^2, doubling Small-End Diameter multiplies the board-foot result roughly fourfold, while doubling Log Length only doubles it. Across the calculator's full 6-48 inch diameter range, diameter swings the board-foot total far more than length swings it across its own 4-24 foot range.

Recovery Rate divides the fixed Doyle board-foot figure by an estimated gross log volume built from the average of the small-end and large-end diameters. A steeper taper makes the large end (and therefore the average diameter) bigger, which inflates the estimated gross volume the log actually contains -- so the same board-foot yield looks like a smaller share of that larger log, and Recovery Rate falls.