Spike's Calculators


Basal Area from Girth Measured @ Breast Height

Spike VM

Calculate the basal area in square feet from the girth of a tree measured at breast height.
Girth of tree is measured at 4.5 feet above the ground.

To calculate for one tree:
Basal Area in sq ft = (girth ÷ 3.14159)² * 0.00545415391


circumference of tree measured @ breast height = 64 inches
64 ÷ 3.14159 = 20.37
20.37 * 20.37 = 415.01 * 0.00545415391 = 2.26354 sq feet of basal area

Basal Area from Tree Girth Measured @ BH

Girth in
Average Bark Thickness in
Decimal Rounding (# of digits in result) #


Diameter in
Area in Square Feet ft²


  1. tree girth measured @ breast height in inches
  2. average thickness of bark in inch
  3. decimal rounding preset @ 5


  1. diameter of tree in inches
  2. basal area of tree in square feet (if no value is used for bark thickness, basal area and diameter of tree includes the bark)
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