The National Champion Valley Oak, California

Before nominating a tree, you need to know 3 measurements: (1) Trunk Circumference (measured in inches), (2) Vertical Tree Height (measured to the nearest foot), and (3) Average Crown Spread (measured to the nearest foot).

American Forests uses the following calculation to determine a tree's total points:

Trunk Circumference + Height + ¼ Average Crown Spread = Total Points

A nominee will replace a registered champion if it has more points. When two trees have scores that fall within 5 points of each other, they are listed as co-champions.

For measuring instructions, click on the links below:

• Trunk Circumference
• Tree Height
• Average Crown Spread

Trunk Circumference

Circumference is measured at 4 ½ feet above ground level in inches.

If the tree forks record in inches the smallest circumference between 4½ feet and the ground below the lowest fork excluding dead branches and epicormic sprouts. Also record the height above the ground line where measurement was taken, in inches.

For more information on measuring trees on a slope, see our FAQ page.

Tree Height

There are many tools that can be used to estimate the height of a tree including something as simple as a stick, but if at all possible height measurements should be confirmed by an expert such as a local arborist, forester, or Big Tree Coordinator.

The vertical height of a tree is measured in feet. It can be measured using an Abney hand level, a hypsometer, a transit, a clinometer, a relascope, a laser or other instrument designed for that purpose.

Alternatively, you can use the stick method:

Hold the stick at its base vertically, making certain that the length of the stick above your hand equals the distance from your hand to your eye. Staying on ground level (or on the same contour as the base of the tree), move away from the tree while sighting the trunk base above your hand. Stop when the top of the stick is level with the top of the tree. You should be looking over your hand at the base of the tree and, moving only your eyes, looking over the top of your stick at the top of your tree. Measure how far you are from the tree and that measurement - in feet - is the tree's height.

Average Crown Spread

Two measurements of the crown spread are taken and recorded (in feet), at right angles to one another. The first is the widest crown spread, which is the greatest distance between any two points along the drip line of the tree. (The drip line is the outline on the ground of the outermost leaves of the crown.) Once the widest spread has been found, turn the axis of measurement 90 degrees and find the crown spread. The two crown spreads are averaged together.