🌲 Basal Area Calculator
Calculate the cross-sectional basal area of a tree trunk from its diameter at breast height, and scale it up for a whole stand of trees.
What this calculator does
The Basal Area Calculator finds the cross-sectional area of a tree trunk at breast height (about 4.5 feet / 1.3 meters above the ground), a standard measurement foresters use to estimate stand density, timber volume, and growth over time.
The formula it uses
Basal area treats the trunk cross-section as a circle: Basal Area = π/4 × DBH². For DBH measured in inches, this simplifies to the standard forestry constant 0.005454 × DBH² for basal area in square feet; for DBH in centimeters, the constant is 0.00007854 × DBH² for basal area in square meters.
Enter a number of trees to scale the per-tree basal area up to a total for a small stand or plot.
A note on accuracy
This calculator computes basal area from a single trunk diameter. Trees with irregular or non-circular trunks, buttressed bases, or forks below breast height will have some measurement error. For whole-forest inventories, foresters typically average basal area across many sample plots or use a wedge prism.