Tree Age Calculator

To determine a Tree’s Age, input Tree Species, Trunk Diameter (measured at breast height), and Growth Factor in tree age calculator. For accurate results, measure Trunk Diameter at 4.5 feet (1.37 meters) above ground level.

Select your preferred Unit System (inches or centimeters). Click Calculate to view Estimated Tree Age, Growth Rate Classification, and Historical Context of when tree likely began growing.

How to Calculate how old a tree is?

To calculate a Tree’s Age, measure Trunk Diameter at Breast Height (DBH) using a measuring tape around the trunk and divide by π (3.14159) to get the diameter. Multiply Diameter by species-specific Growth Factor.

For example, a Red Oak has a Growth Factor of 4.0, while a Silver Maple has 3.0. This method provides an estimate based on typical growth patterns. For more accuracy, consider factors like Soil Conditions, Climate, and Environmental Stress that might affect growth rates.

Tree Growth Factors for Common Species

Tree Category	Species	Growth Factor
Hardwoods	Red Oak	4.0
	White Oak	5.0
	Pin Oak	3.0
	Sugar Maple	5.5
	Silver Maple	3.0
	River Birch	3.5
	American Beech	6.0
	Green Ash	4.0
	White Ash	5.0
	American Elm	4.0
	Hickory	7.5
	Black Walnut	4.5
	Sycamore	4.0
	Cottonwood	2.0
	Redbud	7.0
	Dogwood	7.0
	Black Cherry	5.0
	Honey Locust	3.5
Conifers	White Pine	5.0
	Red Pine	5.5
	Scots Pine	5.0
	Austrian Pine	4.5
	Norway Spruce	5.0
	White Spruce	5.0
	Colorado Blue Spruce	4.5
	Douglas Fir	4.0
	Balsam Fir	5.0
	Eastern Red Cedar	4.0
	Arborvitae	4.0
	Hemlock	6.0
Fruit Trees	Apple	4.5
	Pear	4.0
	Cherry	5.0
	Plum	4.0
	Peach	4.0
Ornamental Trees	Japanese Maple	6.0
	Magnolia	4.5
	Crabapple	4.5
	Flowering Pear	4.0
	Hawthorn	5.0

Formula for Tree Age Calculation

Basic Age Calculation:

Tree Age = Trunk Diameter × Growth Factor
where:
Trunk Diameter = Circumference ÷ π (in inches)
Growth Factor = Species-specific growth rate value

Circumference to Diameter:

Diameter = Circumference ÷ π
where:
Circumference = Trunk measurement in inches/centimeters
π = 3.14159

Growth Rate Categories:

Slow Growth = Less than 12 inches per decade
Medium Growth = 12-24 inches per decade
Fast Growth = More than 24 inches per decade

Example 1: Red Oak Tree

• Tree Species = Red Oak
• Trunk Diameter = 20 inches
• Growth Factor = 4.0
• Calculated Age = 80 years
• Growth Rate = Medium Growth

Example 2: Silver Maple

• Tree Species = Silver Maple
• Trunk Diameter = 30 inches
• Growth Factor = 3.0
• Calculated Age = 90 years
• Growth Rate = Fast Growth

Example 3: White Pine

• Tree Species = White Pine
• Trunk Diameter = 15 inches
• Growth Factor = 5.0
• Calculated Age = 75 years
• Growth Rate = Medium Growth

Example 4: Sugar Maple

• Tree Species = Sugar Maple
• Trunk Diameter = 25 inches
• Growth Factor = 5.5
• Calculated Age = 137.5 years
• Growth Rate = Slow Growth

Example 5: American Elm

• Tree Species = American Elm
• Trunk Diameter = 40 inches
• Growth Factor = 4.0
• Calculated Age = 160 years
• Growth Rate = Medium Growth

What is Tree Age?

Tree Age refers to number of years since a tree began growing from seed or sprout. This measurement helps understand a tree’s Historical Significance, Environmental Impact, and Biological Value. Tree Age can be determined through several methods, including Ring Counting (destructive), Increment Boring (minimally invasive), and Diameter-based Estimation (non-invasive).