# Tree Diameter Calculator

Table of contents

How to calculate the diameter of a tree — DBHHow to use the tree diameter calculatorHow do you find the diameter of the wood inside the bark?How do I calculate the diameter of a tree on a slope?How do I measure the circumference of a leaning tree on level ground?How do I calculate the diameter of a multi-stemmed tree?FAQsWith a simple measuring tape and our tree diameter calculator, you can easily estimate the diameter of a tree — **diameter at breast height (DBH)**.

Using this tree diameter calculator, you can estimate the trunk’s diameter of single and multi-stemmed trees on level ground or a slope. You can also find the diameter of a leaning tree using our tool!

🙋 We use the diameter of a tree to estimate its size and volume, growth and calculate its fertilizer requirements, the potential tree value as a source of wood or biomass, and its carbon storage.

🙋 What is the tree value? Learn it with Omni's tree value calculator!

## How to calculate the diameter of a tree — DBH

We measure the circumference and diameter of a tree at "breast height". We call these measurements the **circumference at breast height (CBH)** and **diameter at breast height (DBH)** of trees.

🙋 Do you know that **Australia, Canada, and Europe**, measure it at $1.3\ \text{m}$ ($4.27\ \text{ft}$) above ground level. In **Japan and Korea**, measure it at $1.2\ \text{m}$ ($3.93\ \text{ft}$). In **New Zealand**, measure DBH at $1.4\ \text{m}$ ($4.59\ \text{ft}$), and in the **United States** at $4.5\ \text{ft}$ ($1.37\ \text{m}$).

To estimate the diameter of a tree:

- Wrap tape tightly around the tree trunk at the DBH height — for example, at 4.5 feet in the US.
- Now, find where the number “0” on your tape aligns with the rest of the tape. This number is the circumference of the trunk.
- Find the diameter using the formula:

where:

- $d$ — The
**diameter**; - $C$ — The
**circumference**; and - $\pi$ — The best mathematical constant, pi!

This is one of the most simple yet important relationships in math: discover it with our circle calculator!

## How to use the tree diameter calculator

Follow these steps to quickly find the diameter of your tree using our calculator:

- Select the
**unit of length**from the drop-down list beside the circumference box. - Enter the value of the
**circumference**you measured at the DBH height. - Read the
**diameter**of the tree from the second field. - You can switch the unit of the diameter if you wish, maybe with our length converter.

🙋 You can calculate the circumference of the tree from the diameter by using our tree diameter calculator in reverse!

## How do you find the diameter of the wood inside the bark?

The diameter we measure outside the bark is the **diameter over-bark** or diameter outside-bark. The **diameter under-bark** or diameter inside-bark is the diameter of the wood inside the bark of a tree.

To calculate the diameter of the wood inside the bark, subtract twice the average bark thickness from the diameter over-bark:

`DUB = DOB − (2 × BT)`

where:

`DUB`

— Diameter under-bark;`DOB`

— Diameter over-bark; and`BT`

— Average bark thickness.

You can just switch to the `Bark details`

sections of our tree diameter calculator to find the diameter under-bark of a tree for both single and multi-stemmed trees!

## How do I calculate the diameter of a tree on a slope?

To find the diameter of a tree on a slope:

- Measure the
**circumference**of the tree at breast height (usually, 1.35 m from the ground)**on its uphill side**. **Divide**the tree circumference by`π (= 3.14)`

to estimate your tree's diameter at breast height (DBH) on a slope.

## How do I measure the circumference of a leaning tree on level ground?

Measuring the circumference of a leaning tree is not a difficult task. Wrap the measuring tape around the leaning tree at breast height (about 1.35 m from the ground) along the **underside face of the trunk** to measure its circumference.

Divide the tree circumference by `π (= 3.14)`

if you want to find the diameter of your leaning tree.

## How do I calculate the diameter of a multi-stemmed tree?

Consider each stem as a separate tree, __if the pith union is below ground__, i.e., the stems are from a common rootstock and are not connected above the ground. So, determine the diameter at breast height (DBH) for each stem separately.

Consider the plant as a single tree, __if the point of pith separation is above ground__. Then, to find the diameter of such a tree:

- Measure the circumference of the
**six largest stems**. - Calculate the
**diameter of each stem**. To check your results, use the tree diameter calculator. - Find the
**square**of each value of diameter. **Add**the squares.- Find the
**square root**of the sum. Congratulations! You've now found the**diameter of your multi-stemmed tree**.

With our tree diameter calculator, you can find the diameter of a multi-stemmed tree both outside and inside the bark (use the `Bark details (multi)`

section for bark calculations). Let's try it!

### How do I measure the diameter of a tree stump?

**The average width of a wider side and a narrow side gives you the stump's diameter**. Measure the width by placing the measuring tape beside the stump on the ground.

### How much does a tree grow in diameter per year?

Most trees grow between **0.2 cm and 0.4 cm** in diameter and between **1.5 cm and 2.5 cm** in circumference per year.

### How do I calculate my 10 year-old oak tree's circumference without a tape?

To find 10 year-old oak tree's circumference:

**Multiply a tree's age (in years) by 2.5 to find its circumference in centimeters**:- circumference (in cm) = 2.5 × age (in years)

- So, your oak tree should have a
**circumference of 25 cm**. - Divide the circumference by 3.14 if you want to find the diameter:
**7.96 cm**.

Every 2.5 cm of girth represents about one year's growth. So by multiplying a tree's age by 2.5 (in some cases, 1.5 or 2), you can roughly estimate a tree's circumference. This method is known as **Mitchell’s Rule**.

### How do I calculate the diameter of a tree of circumference 40 cm?

Divide the tree circumference by `π (= 3.14)`

to find the diameter. So, your tree has a **diameter of 12.7 cm**.