Tree Age Calculator

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Circumference is the distance around the trunk; diameter is the width straight across. Both are measured at breast height.
Wrap a tape measure around the trunk at breast height (4.5 ft / 1.4 m above the ground on the uphill side).
in
Select the closest match to your tree. Growth factors are empirical averages; results are estimates.
Estimated tree ageOld-growth candidate
100years

DBH (inches) x growth factor

Diameter at breast height20in
Diameter at breast height50.8cm
Circumference at breast height62.8in
Growth factor used5
Plausible age range80 to 125 years
100 years
  • Seedling
  • Young
  • Mature
  • Old-growth
  • Ancient

This White Oak is estimated to be about 100 years old.

  • Using a growth factor of 5.0 for White Oak, a trunk diameter of 20.0 inches gives an estimated age of 100 years.
  • Because growth rates vary with climate, soil, sunlight and competition, the plausible range is 80 to 125 years. Urban trees with more space and water often grow faster; forest trees competing for light grow slower.
  • Trees in this age range often have significant ecological value as habitat for cavity-nesting birds, bats, and insects. Mature trees also provide the greatest carbon storage and stormwater interception benefits.

Next stepThis estimate is a non-destructive approximation. For the most accurate age, a professional arborist can use an increment borer to extract and count growth rings without harming the tree.

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