Growth factor

What is a growth factor?

A growth factor is a number used to estimate the age of a tree based on its diameter.

The formula is: Tree age = Diameter at breast height (in cm) × Growth factor Each species has an average growth factor, but it can vary significantly depending on local conditions climate, soil, competition, etc..

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Why use your own growth factor?

Preset growth factors are only averages. In reality, each tree grows differently depending on:

• Climate – temperature, rainfall
• Soil – nutrients, permeability
• Competition – whether the tree grew in a forest or in an open area
• Altitude and care

If you want a more accurate age estimate, you can calculate your own growth factor for local conditions.

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How to calculate your own growth factor

You will need a tree of the same species that has already been felled.

1. Measure the diameter (DBH)Measure the trunk diameter at a height of 1.3 m above the ground – in centimeters.
2. Count the growth ringsCount the annual growth rings on the stump or cross-section. This will give you the actual age of the tree.
3. Calculate the growth factorUse the formula:
   Growth factor = Tree age (growth rings) ÷ Diameter (in cm)
   Example: 80 growth rings ÷ 40 cm = 2.0 (growth factor)
4. For better accuracy (optional)Calculate the factor from several trees and take the average.