Enter the total diameter of a tree at 4.5 feet off the ground into the calculator to determine the basal area.

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## Basal Area Formula

The following formula is used to calculate the basal area of a tree.

BA = F * DBH^2 * N

- Where BA is the basal area
- F is the foresters constant (.005454)
- DBH is the average diameter of the tree at “breast height” which is 4.5 feet (in)
- N is the number of trees per acre.

To calculate basal area, multiply the foresters constant by the average diameter of the trees at breast height squared, then multiply again by the trees per acre.

## Basal Area Definition

Basal area is defined as the total area of an acre that is occupied by tree stems.

## Basal Area Example

How to calculate basal area?

**First, determine the average diameter of the trees at “breast height”.**For this example, we will say we measure 10 trees, and on average they have a diameter of 10 inches at breast height (4.5 feet).

**Next, measure the number of trees per acre.**After counting, we find the number of trees per acre to be 250.

**Finally, calculate the basal area.**Using the formula above, we find the basal area to be .005454*10^2*250 = 136.35 square feet per acre.

## FAQ

**What is basal area?**

A basal area is defined as the total area of an acre occupied by the tree stems.

**What is a foresters constant?**

The foresters constant described above is used to convert inches to square feet.