Enter the diameter at breast height (DBH)—measured 4.5 feet (1.37 m) above the ground—then choose the appropriate calculator tab (single tree, stand per acre/hectare, plot, or angle gauge/BAF) to determine basal area.

Basal Area Calculator

Enter tree diameter (DBH) to get basal area.

One tree
Stand (from plot)
Enter a DBH greater than zero.

—

Copy result
Show calculation ▸

Basal Area Formula

The following formula is used to calculate stand basal area per acre when DBH is in inches and tree density is in trees per acre. 

 BA = F * DBH^2 * N
  • Where BA is the basal area (ft²/acre)
  • F is the forester’s constant (0.005454…), equal to (π/4) ÷ 144
  • DBH is diameter at “breast height,” measured 4.5 feet (1.37 m) above the ground; in this formula DBH is in inches
  • N is the number of trees per acre.

To calculate stand basal area, multiply the forester’s constant by DBH squared, then multiply by the trees per acre. For a single tree basal area in square feet, use BAtree = 0.005454 × DBH² (DBH in inches).

Basal Area Definition

Basal area is the sum of the cross-sectional areas of tree stems at breast height, expressed per unit of land area (commonly ft²/acre or m²/ha).

Basal Area Example

FAQ

What is basal area?

Basal area is the sum of the cross-sectional areas of tree stems at breast height, expressed per unit of land area (commonly ft²/acre or m²/ha).

What is a foresters constant?

The forester’s constant (0.005454…) combines (π/4) with the conversion from square inches to square feet, so DBH in inches can be converted into basal area in ft² (per tree, or per acre when multiplied by trees per acre).