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

Stand basal area
Single tree
Plot / multiple trees
Angle gauge / BAF

Quick stand stocking: use DBH and trees per acre (or hectare) to get basal area, or solve for trees/diameter instead.

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).