Tree Diameter Calculator

With 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 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.

To estimate the diameter of a tree:

1. Wrap tape tightly around the tree trunk at the DBH height — for example, at 4.5 feet in the US.
2. Now, find where the number “0” on your tape aligns with the rest of the tape. This number is the circumference of the trunk.
3. 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!

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

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

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!

To find the diameter of a tree on a slope:

1. Measure the circumference of the tree at breast height (usually, 1.35 m from the ground) on its uphill side.
2. Divide the tree circumference by π (= 3.14) to estimate your tree's diameter at breast height (DBH) on a slope.

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.

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:

1. Measure the circumference of the six largest stems.
2. Calculate the diameter of each stem. To check your results, use the tree diameter calculator.
3. Find the square of each value of diameter.
4. Add the squares.
5. 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!