This advanced tree diameter calculator is a tool used to determine the width of a tree trunk at a specific height, typically at breast height (DBH).
A forester needs to assess the size of an oak tree in a park. By using this tree measurement calculator, they can quickly determine that the tree has a diameter of 24 inches (61 cm) at breast height, providing valuable information about the tree’s size and potential age.
Tree Diameter Calculator
| Circumference (in) | Circumference (cm) | Diameter (in) | Diameter (cm) |
|---|---|---|---|
| 31.4 | 79.8 | 10 | 25.4 |
| 62.8 | 159.5 | 20 | 50.8 |
| 94.2 | 239.3 | 30 | 76.2 |
| 125.6 | 319.0 | 40 | 101.6 |
| 157.0 | 398.8 | 50 | 127.0 |
| 188.4 | 478.0 | 60 | 152.4 |
| 219.9 | 558.0 | 70 | 177.8 |
| 251.3 | 637.2 | 80 | 203.2 |
| 282.7 | 716.4 | 90 | 228.6 |
| 314.2 | 797.0 | 100 | 254.0 |
| 345.6 | 877.0 | 110 | 279.4 |
| 377.0 | 957.0 | 120 | 304.8 |
| 408.4 | 1037.0 | 130 | 330.2 |
| 439.8 | 1117.0 | 140 | 355.6 |
| 471.3 | 1197.0 | 150 | 381.0 |
- Inches to cm: multiply by 2.54
- Cm to inches: divide by 2.54
Tree Diameter Formula
The basic formula for calculating tree diameter is:
Diameter = Circumference ÷ π
Where π (pi) is approximately 3.14159.
A tree’s circumference is 62.8 inches, its diameter would be: 62.8 ÷ 3.14159 ≈ 20 inches
For a tree with a circumference of 157 cm, the diameter would be: 157 ÷ 3.14159 ≈ 50 cm
How to Find the Diameter of a Tree?
- Measure at breast height: This is typically 4.5 feet (1.37 meters) above ground level on the uphill side of the tree.
- Use a diameter tape: This specialized tape gives a direct diameter reading when wrapped around the tree.
- Alternatively, use a regular measuring tape: Measure the circumference and divide by π to get the diameter.
- For irregular trunks: Take multiple measurements and calculate the average.
- Account for obstructions: If there are branches or burls at breast height, measure just above or below the obstruction.
- For leaning trees: Measure perpendicular to the trunk axis, not parallel to the ground.
What is the Diameter of a Tree?
The diameter of a tree refers to the width of its trunk measured at a standard height. It’s a key indicator of a tree’s size, age, and overall health. Diameters can range from a few inches for young or small species to several feet for ancient or large species.
Tree Diameter to Height Ratio
A typical ratio might be 1:50 to 1:100, meaning for every unit of diameter, the tree is 50 to 100 units tall.
The diameter to height ratio is an important metric in forestry. Generally, as trees grow taller, their diameter also increases, but not always at the same rate. This ratio can vary depending on:
- Species: Some trees grow tall and slender, while others are shorter and wider.
- Age: Young trees often have a lower diameter to height ratio than mature trees.
- Environmental conditions: Factors like soil quality, water availability, and competition affect this ratio.
What Tree Has a 40 Foot Diameter Trunk?
Very few trees reach such an enormous size. The Giant Sequoia (Sequoiadendron giganteum) is one of the few species known to achieve this scale. The famous “General Sherman” tree in California has a diameter of about 36 feet (11 meters) at its base, approaching the 40-foot mark.
What is Considered a Large Tree Diameter?
The definition of a “large” tree diameter varies by species and region. However, some general guidelines include:
- For many common deciduous trees, a diameter over 24 inches (61 cm) is considered large.
- In old-growth forests, trees over 40 inches (102 cm) in diameter are often classified as large.
- For smaller species, like dogwoods or fruit trees, 12 inches (30 cm) might be considered large.
