Tree Value Calculator

Standing timber is valued in two steps: estimate how many board feet of lumber the merchantable stem will yield, then multiply by the stumpage price buyers pay for that species and grade. A board foot is 144 cubic inches, nominally a piece 12 by 12 inches by 1 inch thick. Log rules convert a diameter and a length into board feet, and they disagree because each embeds different assumptions about saw kerf, slab waste, and how logs are broken down. The Doyle rule, (D minus 4) squared times L divided by 16, subtracts a flat 4 inch allowance for slabbing, which is far too severe on small logs and too generous on large ones: a 10 inch log scales at only 36 board feet per 16 foot length while a 30 inch log of the same length is credited with 676. Scribner is a diagram rule built from drawn boards, and the International 1/4 inch rule assumes a 1/8 inch saw kerf plus 1/16 inch shrinkage per board and tracks true yield most closely. Merchantable height is the stem length usable for lumber, running from the stump to the first serious defect, the base of the live crown, or the point where diameter drops below about 8 to 10 inches, and it is normally expressed in 16 foot logs. Prices are the largest source of uncertainty. Species defaults from 0.20 dollars per board foot for yellow poplar to 2.50 for black walnut are broad regional averages; actual stumpage swings with log grade, haul distance to a mill, tract size, and local demand, and veneer-quality butt logs can trade at several times sawlog rates. Any figure produced without a grade assessment is an order-of-magnitude estimate, not an appraisal.

Log rules appeared in the American northeast during the nineteenth century, when timber began changing hands by measured volume rather than by the piece. The Doyle rule is attributed to Edward Doyle and dates to roughly 1825; its arithmetic was simple enough to be done in the woods, which is why it spread through eastern hardwood markets and, despite decades of criticism from mensurationists, remains the customary basis of many hardwood sales in the southern and central United States. J. M. Scribner published his rule in 1846 in Scribner's Lumber and Log Book, deriving it graphically by drawing circles of each diameter and packing them with boards, a method that gives more realistic small-log values than Doyle. The International rule was the first built from a formula rather than a diagram or a rule of thumb. Judson F. Clark developed it in 1906, allowing for taper along the log and for a specific saw kerf, and it was later restated in a 1/4 inch kerf version that became the standard for research and national inventory work; the USDA Forest Service uses it for Forest Inventory and Analysis timber volume reporting. Because the three rules can differ by more than 30 percent on the same log, sale contracts must name the rule being used. Stumpage price reporting professionalized separately during the twentieth century, with regional services such as Timber Mart-South, established in 1976, publishing quarterly survey prices that landowners and consulting foresters use as negotiating benchmarks.