The most accurate method is to count the year rings. Each annual ring is one year. However, if the tree is standing, we can only find the approximate age of the tree. In order to find this approximate age we must use this method.

1. Measure the circumference of the tree, 54 inches above ground level.
2. Calculate the diameter.
3. Multiply the diameter by the growth factor.

EXAMPLE: ( feet >>m )

The white oak has a circumference of 351 cm / 138.2 in

The diameter is calculated by dividing the circumference (in) by 3.14.
( 3.14… Pi (π) mathematical constant. Pi is the ratio of the circumference of a circle to its diameter)
(138.2 in / 3.14 = 44 in)

Multiply the result / diameter by the Growth Factor as shown in the table.
White oak = 5
44 in x 5 = 220

According to this method, the oak tree is approximately 220 years old.

Clearly, in an environment where there is plenty of water, the increments will be greater than in a rocky subsoil where it is dry. Therefore, these results are only approximate. There are other scientific methods for accurately measuring growth that cannot be routinely applied because of the irreversible damage to the tree that would occur if not used professionally.

TREE / GROWTH FACTOR

American beech / 6
American elm / 4
American sycamore / 4
Austrian pine / 4.5
Black cherry / 5
Black maple / 5
Black walnut / 4.5
Common horsechestnut / 8
Colorado blue spruce / 4.5
Cottonwood / 2
Douglas fir / 5
European beech / 4
European white birch / 5
Green ash / 4
Ironwood / 7
Kentucky coffee tree / 3
Littleleaf linden / 3
Northern red oak / 4
Norway maple / 4.5
Norway spruce / 5
Pin oak / 3
Redbud / 7
Red maple / 4.5
Red pine 5.5
River birch / 3.5
Scarlet oak / 4
Scotch pine / 3.5
Shagbark hickory / 7.5
Shingle oak / 6
Shumard oak / 3
Silver maple / 3
Sugar maple / 5.5
Sweet gum / 4
Tulip tree / 3
White ash / 5
White fir / 7.5
White oak / 5
White pine / 5
Yellow buckeye / 5