Root Zone Protection Calculator

Calculate the critical root zone and minimum protection radius for trees near construction.

Trunk Diameter (DBH)

Estimated Tree Age

years

Soil Type

Construction Type

Tab to move between fields

CRZ Radius

25.2 ft

≈ 5 adult heights

CRZ Area1,995 sq ft

Min Protection Radius25.2 ft

Protection Fence Length158 ft

Penalty Zone Depth0 ft

How to Use This Calculator

Enter Trunk Diameter (DBH), Estimated Tree Age, and Soil Type.
Set Construction Type.
Review the CRZ Radius (ft) result.
Use CRZ Area (sq ft) and Min Protection Radius (ft) to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Trunk Diameter (DBH)

Trunk Diameter (DBH): Diameter at breast height (4.5 ft above ground).
Estimated Tree Age: Approximate age of the tree in years.
Soil Type: 1=Sandy (roots spread wider), 2=Loam, 3=Clay (roots more compact).
Construction Type: 1=Trenching (most damaging), 2=Grading, 3=Paving (least damaging).

Identify Input Parameters
4 parameters
Trunk Diameter (DBH) = 18, Estimated Tree Age = 40, Soil Type = 2, Construction Type = 1 = 4 input(s) provided
Calculate CRZ Radius
CRZ Radius
25.2 = 25.2
Calculate CRZ Area
CRZ Area
1995 = 1995
Calculate Min Protection Radius
Min Protection Radius
25.2 = 25.2

Engine last updated July 28, 2026. Checked against 2 independently-derived tests — how we verify calculators.

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