How a Champion Tree Is Scored: Girth, Height and Crown

How the American Forests formula scores a tree, worked step by step on the national champion American sycamore: 432 + 124 + 88 ÷ 4 = 578 points.

The tree in this explainer

American sycamore (Platanus occidentalis), Ashland County, Ohio. National champion · last measured 2013.

Circumference: 432 in
Height: 124 ft
Crown spread: 88 ft
Total: 578 points

The register publishes the three results, not the field notes. The slope, the trunk flare, the distances and angles, the leaning limb and the split of the crown into 96 and 80 feet are a drawn reconstruction, chosen so that measuring it by the handbook's rules returns the register's own numbers.

A champion is decided by points: girth in inches, height in feet, a quarter of the crown.

American Forests scores every nominated tree with one formula: trunk circumference in inches, plus height in feet, plus one quarter of the average crown spread in feet. The highest score for a species makes the national champion. This explainer follows the formula on a real register entry, the champion American sycamore in Ashland County, Ohio, and rebuilds each of its three numbers.

Girth is taken 4.5 feet up the trunk, the forester's breast height.

Circumference is measured with a diameter tape wrapped around the trunk 4.5 feet above the ground, roughly chest height; foresters call it breast height. The result is read in inches and counts one point per inch, so girth usually carries most of the score. If the trunk leans, the tape goes on at right angles to the lean, not level with the ground.

On a slope, the 4.5 feet start from the midpoint between uphill and downhill ground.

On a slope the trunk meets the ground at two heights. The handbook's mid-slope rule marks 4.5 feet above the uphill contact and 4.5 feet above the downhill contact, then takes the girth midway between the two marks, where the seed is judged to have fallen. On the drawn 12-degree slope the uphill mark alone would read 416.3 inches and the downhill mark 467.6; mid-slope reads 432.

Tangent method: a level distance and two angles. It trusts the top to stand above the base.

The traditional tangent method needs a level distance to the trunk and two angles, one up to the top and one down to the base. Height is the distance times the difference of the two tangents. The formula assumes the top stands straight over the trunk. This sycamore's highest twig sits 12 feet beyond the trunk, so from 150 feet away the method returns 117.6 feet instead of 124.

Sight a limb leaning toward you as the top, and the tangent method adds 12.5 feet.

Now the measurer mistakes a limb leaning toward them for the top. The tangent formula projects that point back over the trunk, as if it stood there. The limb is 110 feet up and 40 feet closer than the trunk, yet the calculation returns 136.5 feet, 12.5 feet the tree does not have. Carried into the formula, the score becomes 590.5 points instead of 578.

The sine method measures straight to the real top, so where the top leans stops mattering.

The handbook's preferred method replaces the level distance with two laser shots, the straight-line distance to the top and to the base, each multiplied by the sine of its angle. That gives the vertical height of each point above or below the eye, wherever it stands. The real top yields 124 feet. The leaning limb yields 110, lower, which exposes it as the wrong target.

Crown spread: the widest spread and the one at right angles, averaged, then divided by four.

Crown spread is read from above, as the outline of the crown projected onto level ground. In the two-axis method the measurer finds the widest spread, then the widest spread at right angles to it, and averages the two. The register lists an 88-foot average for this sycamore; the split into 96 and 80 feet is drawn for illustration. A quarter of 88 adds 22 points.

Add them up: 432 + 124 + 22 = 578 points, the register's own total.

Girth 432, height 124 and a quarter of the 88-foot crown, 22, give 578 points, exactly the total the national register lists for this tree. The shares show why girth settles most contests: here it carries 74.7 percent of the score, height 21.5 percent and the crown 3.8 percent. The quarter weight keeps crown spread, the hardest of the three to measure, from moving the result much.

Sources: American Forests Champion Trees Measuring Guidelines Handbook (Leverett & Bertolette) · National Champion Tree Program, 2024 Register measurement data (University of Tennessee) · National Champion Tree Program, Champion Tree Registry · American Forests, Champion Trees