Tree Age From Girth Calculator

Work out tree age from girth instantly with clear inputs, formula shown and shareable results.

About Tree Age From Girth Calculator

Converts circumference to diameter and applies the species growth factor used in the standard arboricultural age tables.

Formula

Growth factor method

Diameter = circumference / pi; age (years) = diameter in inches x species growth factor

Worked example

With the default values below, Tree Age From Girth Calculator returns Estimated age of 84.6. Change any input above and every figure here is recalculated in your browser.

Inputs used

Trunk circumference at breast heightaccepts 5–2,000 cm: 150 cm
Species growth factoraccepts 1–10: 4.5

Results

Estimated age: 84.6 years
Trunk diameter: 47.75 cm
Trunk diameter: 18.798 in
Average girth increase per year: 1.773 cm/yr

Step by step

1Values used
2Growth factor method
3Estimated age= 84.6 years
4Trunk diameter= 47.75 cm
5Trunk diameter= 18.798 in
6Average girth increase per year= 1.773 cm/yr

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How accurate is the method?

Within roughly 20% for open-grown trees; crowded or stressed trees grow far more slowly than the factor assumes.

Where is girth measured?

At breast height, 1.3 to 1.4 metres above ground on the uphill side of the trunk.