Spike's Calculators


Number of Trees and Tree Spacing Calculated from Basal Area

Calculate the number of trees and the spacing from an average tree diameter and basal area in square feet per acre.

Example Calculation
A basal area of 125 square feet per acre
the average tree diameter is 14 inches
B = DBH² * 0.00545415391

calculate the basal area of one tree
14² = 196 * 0.00545415391 = 1.069 ft²
divide the total basal area by the tree basal area to get the number of trees per acre
125 ÷ 1.069 = 116 trees per acre. 
To find the spacing between the trees, divide one acre (43560 square feet) by the amount of trees;
43560 ÷ 116 = 375.5172413793103 
Assuming the spacing between these trees is the same for in row and in between rows spacing, take the square root of this amount.
The square root of  375.5172413793103 = 19.4 
The spacing between the trees = 19 feet (rounded)

Trees Number and Diameter

Average diameter (dbh) in
Total basal area per acre ft²/ac


Trees per acre #/ac
Tree spacing ft


  1. he average diameter of the trees in inches (diameter measured at breast height)
  2. total basal area of all the trees per acre, in square feet


  1. the amount of trees per acre
  2. the spacing between the trees in feet
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