Biology
Estimate tree age from trunk circumference and a species growth factor.
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Change any value — everything updates instantly.
Tape measure around the trunk.
e.g. silver maple 3.0, red maple 4.5, white oak 5.0, sugar maple 5.5.
Try an example
Estimated age
86 years
This means the tree is roughly 86 years old.
What you are seeing
Rings appear from the centre outwards as the tree grows.
Each drawn ring stands for about 5 years.
The trunk reaches 19.1 in DBH at about 86 years.
DBH
19.1 in
Circumference ÷ π.
Growth per year
0.22 in/yr
Average diameter added each year.
Result explanation: Approximate age
About 86 years.
Real-life comparison: With a factor of 5.5 it would be 105 years.
Low, normal or high? Treat this as a rough estimate — urban and open-grown trees often grow faster than forest trees.
Estimated age against circumference
How to read this chart: Age rises in a straight line with trunk size for a given species.
Finds DBH from circumference and multiplies by the species growth factor.
Roughly 86 years old.
Only a ring count from a core or stump gives the true age.
Growth factors are averages for typical conditions.
Diameter times years per inch of growth.
Age = (C ÷ π) × GF
Symbols
Why this formula works
The growth factor is the average years a species takes to add one inch of diameter.
Unit check
in × yr/in = yr ✓
Worked example
Common mistakes
The tree is about 86 years old.
It can be off by decades; site, water and competition change growth.
Arborist tables based on average diameter growth per species.
An increment borer core gives an accurate count without felling.
Look up its growth factor from a local extension office.
Reviewed 2026-09-25 · Next review 2027-09-25
Important limitation. A rough estimate only; not suitable for legal or heritage decisions.
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