Calculating the Diameter of a Tree – DBH
To measure a tree’s circumference and diameter, we do so at “breast height.” These values are known as the circumference at breast height (CBH) and diameter at breast height (DBH).
Explanation:
- The form takes the tree’s circumference and pi (π).
- On clicking “Calculate Diameter,” the diameter is calculated using the formula:
diameter = circumference / π - The result is displayed in the “Diameter” field.
Multi-Stemmed Tree Diameter Calculator
| Field | Input |
|---|---|
| 1st Stem Circumference (cm) | |
| 2nd Stem Circumference (cm) | |
| 3rd Stem Circumference (cm) | |
| 4th Stem Circumference (cm) | |
| 5th Stem Circumference (cm) | |
| 6th Stem Circumference (cm) | |
| Diameter |
🤔 Did you know that the height used for DBH measurements differs across countries? For example:
- In Australia, Canada, and Europe, DBH is measured at 1.3 meters (4.27 feet) above the ground.
- In Japan and Korea, it’s taken at 1.2 meters (3.93 feet).
- New Zealand measures DBH at 1.4 meters (4.59 feet), while in the United States, it’s at 4.5 feet (1.37 meters).
How to Estimate Tree Diameter:
Wrap a measuring tape around the tree trunk at the appropriate DBH height (e.g., 4.5 feet in the U.S.).
Note the number where the “0” point on your tape meets the other end—this is your tree’s circumference.
Use the following formula to find the diameter:
Where:
- d is the diameter,
- C is the circumference, and
- π is the constant (approximately 3.14).
This simple equation is foundational in mathematics—explore it further with a circle calculator!
Using the Tree Diameter Calculator
Follow these quick steps to find your tree’s diameter:
- Choose your preferred unit of length (e.g., meters or feet) from the calculator.
- Enter the circumference you measured at DBH height.
- Read the calculated tree diameter from the results.
You can even reverse the calculation and input the diameter to find the circumference!
Determining Diameter Inside the Bark
When measuring the outer tree diameter, it’s known as diameter over-bark (DOB). If you’re interested in the diameter of the wood beneath the bark, you need to find the diameter under-bark (DUB). This can be done by subtracting twice the bark thickness from the outer diameter:
[DUB = DOB – (2 \times BT)]
Where:
- DUB is the diameter under-bark,
- DOB is the diameter over-bark, and
- BT is the average bark thickness.
Switch to the bark details section of the tree diameter calculator to compute the under-bark diameter for single or multi-stemmed trees!
How to Measure a Tree’s Diameter on a Slope
When dealing with a tree on a slope, measure the circumference on the uphill side at breast height (typically 1.35 meters). Then, divide the circumference by π (3.14) to calculate the tree’s diameter.
Measuring a Leaning Tree on Flat Ground
For leaning trees, wrap the measuring tape around the underside of the trunk at breast height (around 1.35 meters). Divide the measured circumference by π (3.14) to get the diameter.
Calculating the Diameter of Multi-Stemmed Trees
If the stems emerge from a common rootstock but don’t connect above ground, treat each stem separately. Measure the DBH for each one individually.
However, if the pith separation occurs above ground, treat the plant as a single tree. To find the diameter:
- Measure the circumference of the six largest stems.
- Calculate the diameter of each stem.
- Square each diameter value.
- Add the squared values together.
- Find the square root of the sum.
With this, you’ll determine the total diameter of a multi-stemmed tree. The tree diameter calculator can also help you find the diameter both outside and inside the bark. Explore the Bark Details (Multi) section for further calculations!
This rewritten version maintains the integrity of the original formulas and facts while presenting the information uniquely.
