
ODNR Division of Forestry How To Measure A Tree

Additional Resources

America's forestry movement actually started in Ohio with the creation of the American Forestry Association in Cincinnati in 1875.

Division of Forestry
2045 Morse Rd.
Building H1.
Columbus, OH 43229

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How To Measure

There are three measurements required to nominate a champion tree:

Trunk Circumference (measured in inches)
Vertical Tree Height (measured to the nearest foot)
Average Crown Spread (measured to the nearest foot)

Trunk Circumference
The circumference of the tree is to be measured at 4.5 feet above the ground on the uphill side of the tree. If the tree forks below 4.5 feet then measure the circumference of the largest stem at 4.5 feet. If the tree forks at 4.5 feet, then measure the circumference at the smallest place below the fork.

The best tool to use to measure circumference is a flexible tape measure or one can use a non-stretch string and a ruler. To ensure an accurate measurement make sure the tape or string is perpendicular to the axis of the trunk and is not twisted. Remember that all circumference measurements need to be made in inches.

Tree Height
The total height of the tree is considered to be the distance between the base of the tree trunk and the topmost twig. The most reliable measuring tools are the Abney hand level, clinometer, or transit. If these tools are not available, one can measure the tree’s height with a straight stick.

First, measure the distance from your eye to the joint of your thumb and index finger (arm is stretched out).
Next, hold the stick straight up and down at arm’s length in front of you and make sure the portion above your hand is the same as what you measured from your eye to your hand.
Step backwards until the tree’s base appears to rest on the top of your fist, while the top of the stick appears to touch the top of the tree. At this exact point, the height of the tree is equal to the distance from the base of the tree to you.
Place a stake in the ground and measure (in feet) from the trunk of the tree to the stake to find the height!

Average Crown Spread
For the crown spread, you will need two sets of measurements to get an average. First, step away from the tree and take a look at the tree’s crown. More than likely the tree is not symmetrical, and it has a narrow and a wide side. Measure from the outermost branch on one side to the outermost branch on the other side of a tree. The measurement should be to the nearest foot and be done for both the narrow spread and the wide spread.

Then average these two measurements by adding them together and dividing by two:
(wide spread + narrow spread) / 2 = Average Crown Spread

Scoring Your Tree
Champion trees are determined on the basis of points awarded in the following manner:

One (1) point for each inch in circumference
One (1) point for each foot in height
One-fourth (1/4) point for each foot in average crown spread
Total points = circumference in inches + height in feet + one fourth of the av. crown spread in feet

Once you have the total points of your tree, compare it with its species on the Ohio Tree List and if your tree scores higher than the current champion or is close in points to a current champion, submit your nomination.

If you have difficulty in measuring a Big Tree, measure the tree to the best of your ability and note on the nomination form that you have estimated or were unable to measure.

All State and National champion trees will be checked by a big tree program representative.