How To Tell The Age Of A Tree

  • By: The DIG for Kids
  • Time to read: 5 min.

Trees are so important for humans and all life on earth. You’re probably aware of how they provide us with oxygen but they’re also essential for maintaining balance in the soil which provides nutrients for other things to grow. In short, without trees, we wouldn’t be able to grow crops and plants. 

While it might not be immediately obvious, knowing the age of trees is important. For some people, it’s a matter of curiosity, but how do you tell the age of a tree?

The most common method is by looking at the tree rings, but it’s not simply a case of counting them. The condition of these rings tells us a lot about the environment the tree has been exposed to over the course of its life.

Let’s take a closer look at how to tell the age of a tree and some other interesting tree related facts!

Why Would You Need To Know The Age Of A Tree?

You might think that there is very little point in knowing the age of a tree. After all, it’s there in the ground and regardless of how old it is, if it’s doing well, it doesn’t really matter, right?

Well the truth is that knowing the age of a tree is actually very important. For scientists and the forestry industry, this is essential because it can provide wider information. Knowing the age of an individual tree within a stand can allow scientists to estimate the average age of all trees in the same stand. 

Moreover, this information can give them an idea of how fast local trees are growing according to environmental factors. This also shows the quality of the site and tells us the average height for specific tree types within the area according to their age. 

It’s also important in the forestry industry as knowing the age and comparative size of the trees will allow us to estimate the potential value of the site in the future.

But it isn’t only industries that require this type of information. Landowners can benefit from knowing the age of their trees as this will show how well certain tree types do in the soil there. Moving forward, you’ll have a better idea of what trees to plant and where to plant them.

How Do You Tell The Age Of A Tree?

The method you use to tell the age of the tree will depend on its current condition.

Cut Trees

If you have a tree stump or are going to cut the tree then it is much easier to determine the age as the rings inside the trunk will be exposed. Cutting the tree is the only way you’ll be able to see inside but you’ll get the most accurate information this way. 

Once you can see the rings, counting the dark rings will tell you how old the tree is. But what’s really fascinating is that these rings don’t only tell you how old the tree was but also what it has been through in its lifetime!

There are many ways that the rings might appear. There could be changes with the thickness, colour, shape and other aspects. Each of these things tells you something about what the tree has been exposed to. 

If the rings are particularly narrow then this could be indicative of very dry conditions or problems with insects. However, if the rings are much wider, then this tells us that there may have been a very wet season which allowed the tree to grow more in that particular year. 

Dark rings inside the tree’s trunk tell us that the tree had a growth spurt during late summer or early autumn. How do we know this? It’s all to do with the size of the cells. When trees grow in spring or early summer, the cells are much larger and have a thinner wall whereas when the tree grows later in the year, the cells have a thicker wall and are much smaller which produces a darker ring. 

Living Trees

Now, we wouldn’t suggest cutting down one of your healthy trees all in the name of finding out how old it is. Not many people would even want to do this but then how do you determine its age?

While it is a little more difficult and you won’t get an accurate age, it is still possible to get a fairly accurate guess. Please be aware that cutting into a tree even just a small amount will cause damage so only do this if you’re willing to lose the tree. 

If you’re not, then you might try this method. You’ll need to start by measuring the circumference of the trunk in inches. From this measurement, you will be able to work out the diameter of the tree by dividing the circumference by pi.

When you have this measurement, you’ll need to multiply it by the species average growth factor. You can find a chart for this in the image below. This will give you the rough age of the tree. For this method to work, you will need to be confident in the species of the tree. If you are at all unsure you can contact a professional or there are smartphone apps that very reliably identify plants and trees by their leaves. All you need to do is take a photo of the leaves and the app will scan this and come up with the species. 

What Is The Oldest Tree In The World?

In the White Mountains in California, USA, there is a Great Basin Bristlecone Pine tree that is thought to be 5062 years old! However, this tree was only recently discovered and before that another one, of the same species, held the record for the oldest tree at 4852 years old. The tree was recognised as the oldest in the world for many years and was even given the name, Methuselah. 


Knowing the age of a tree can be beneficial in a number of ways. The most accurate way to determine this is by counting the rings inside the trunk. In order to do this, the tree must be cut which isn’t always ideal. 

However, there is an alternative method which will give you a rough estimate of how old your tree is without having to cause any damage to it. Who knows, you might discover that a tree on your property is the new world record holder for being the oldest tree known to man!

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