Tree Age Calculator

Created by Mehjabin Abdurrazaque
Reviewed by Wojciech Sas, PhD candidate and Rijk de Wet
Last updated: Sep 28, 2022

The tree age calculator guides you on how to calculate the age of a tree to understand its ecological and economical benefits, as you can learn at the tree value calculator. Our tool also tells you how much a tree grows in diameter or circumference in the given time so that you can design your yard suitably.

We also try to answer some interesting questions like:

  • Do trees die of old age?
  • How to tell how old a tree is by counting its rings?

And, don't forget to check our tree growth factor chart to find the fast-growing trees in your neighborhood!

How to calculate the age of a tree?

The formula for calculating a tree's age is

age=gfdbh\text{age} = \text{gf}\cdot \text{dbh}

Where:

  • age\text{age} — The tree's age in years;
  • gf\text{gf} — The tree growth factor; and
  • dbh\text{dbh} — The diameter at breast height in inches.

Follow these steps to find your tree's age using this formula:

  1. Measure the circumference at breast height (cbh) of the tree trunk using a measuring tape at 4.5 feet (1.3 meters) above the ground.
  2. Divide the circumference cbh by pi (≈3.14) to obtain its diameter at breast height (dbh\text{dbh}).
  3. Convert dbh\text{dbh} to inches.
  4. Multiply the diameter in inches with the tree species' growth factor.

Growth factor of a tree
To determine a tree species' growth factor, scientists first estimate the actual age of trees of that species by counting their growth rings. Then, they divide the trees' diameters at breast height (we met this quantity at our tree diameter calculator) with their actual ages to obtain the tree species' growth factor.

How to use tree age calculator?

It's very simple: select the type of tree and input the tree's circumference or diameter. 😎✨

Suppose you want to know the age of your red maple with a circumference of 6 feet and 3 inches (= 2 feet in diameter). To determine your tree's age using our tool, you'd follow these steps:

  1. Scroll down the tree species' drop-down list and select Red maple.
  2. To calculate your tree's age from its circumference:
    • Choose the unit for circumference at breast height (cbh\text{cbh}) from the drop-down list beside its input box. For your red maple, the unit is feet/inches. Then enter the circumference of 6 feet and 3 inches (if you are not familiar with this way to express length, visit the feet and inches calculator).
    • Enter the tree's circumference in the input box — 66 in the box to the left of ft\text{ft} and 33 in the box to the left of in\text{in}.

Ta-da! The calculator shows your tree's diameter at breast height (dbh\text{dbh}) is 61 cm61\ \text{cm} (you can convert the length to obtain the diameter in feet or feet and inches) and its age 107 years107\ \text{years}! It's a centenarian!

If you want to tell the tree's age from its diameter:

  • Choose the unit for diameter at breast height from the drop-down list beside its input box — feet ($$\text{ft}$$).
  • Enter your tree's diameter in the input box — 22.

🙋 If you can't find your tree in the list, enter your tree's growth factor in the input box for Growth factor. Most tree species have growth factors of 3, 4, or 5.

Did you know that you can roughly estimate your tree's birthday using our date calculator! Just enter your tree's age in days and today's date in our tool, and you can obtain a date close to your tree's actual birthday.

Tree growth factor chart — the smaller, the faster!

You can use our tree growth factor not only to calculate your tree's age but also to learn which trees grow faster than your tree. The rule is: The smaller the tree growth factor, the faster the tree grows.

While you are here, check out our tree spacing calculator. It will help you determine the correct distance for planting different types of trees.

The tree growth factor chart for many different species of tree.

Tree species

Growth factor

American beech

6

American elm

4

American sycamore

4

Austrian pine

4.5

Basswood

3

Black cherry

5

Black maple

5

Black walnut

4.5

Black willow

2

Box elder

3

Bradford pear

3

Common horse chestnut

8

Colorado blue spruce

4.5

Cottonwood

2

Dogwood

7

Douglas fir

5

European beech

4

European white birch

5

Green ash

4

Honey locust

3

Ironwood

7

Kentucky coffee tree

3

Littleleaf linden

3

Northern red oak

4

Norway maple

4.5

Norway spruce

5

Pin oak

3

Quaking aspen

2

Redbud

7

Red maple

4.5

Red pine (Norway pine)

5.5

River birch

3.5

Scarlet oak

4

Scotch pine

3.5

Shagbark hickory

7.5

Shingle oak

6

Shumard oak

3

Silver maple

3

Sugar maple

5.5

Sweetgum

4

Tulip tree

3

White ash

5

White fir

7.5

White oak

5

White pine

5

Yellow buckeye

5

FAQ

Do trees die of old age?

As a tree ages, its respiring tissue increases, but the photosynthetic area (leaf surface area) remains somewhat constant. Consequently, an older tree allocates more carbohydrates for life-sustaining respiration and less carbohydrate for root and stem elongation and repair, which initiates its senescence (physiological deterioration) phase. The tree becomes more vulnerable to diseases and other natural enemies and eventually becomes a snag.

How can I identify the fast-growing trees near me?

It's easier to find out which trees grow faster than others using the tree growth factor chart. The smaller the growth factor, the faster the tree grows!

How do I calculate an oak tree's age by diameter?

To determine an oak tree's age by diameter:

  • Convert the diameter to inches.
  • Multiply the diameter with the tree species' growth factor.
  • The product is the tree's age in years!

For example, the age of your pin oak tree with a diameter of 3 ft at breast height (dbh) is 3 (the growth factor) times 39 (dbh in inches) = 117 years!

How do I count tree rings to estimate its age?

Each dark ring of the tree trunk represents a cycle of seasons, or one year. So, the total number of dark rings tells us the age of the tree in years. Count from the innermost dark ring to the outermost.

Mehjabin Abdurrazaque
Tree species
Select...
Growth factor
Circumference at breast height
in
Diameter at breast height
in
Age
yrs
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