Tree Risk Assessment Calculator

Evaluate tree failure risk using ISA-style assessment with failure likelihood, target value, and impact severity.

Failure Likelihood

Target Value

Impact Severity

Tree Size

Tab to move between fields

Risk Rating (1-16)

Category (1=Low, 4=Extreme)1

Inspection Every36 months

Mitigation Priority (1-4)1

Liability Score (1-10)2

How to Use This Calculator

Enter Failure Likelihood, Target Value, and Impact Severity.
Set Tree Size.
Review the Risk Rating (1-16) result.
Use Category (1=Low, 4=Extreme) and Inspection Every (months) to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

What each input means

Failure Likelihood: 1=Improbable, 2=Possible, 3=Probable, 4=Imminent.
Target Value: 1=Low (open field), 2=Medium (walkway, fence), 3=High (house, playground).
Impact Severity: 1=Negligible, 2=Minor, 3=Significant, 4=Severe (structural damage or injury).
Tree Size: 1=Small (< 30 ft), 2=Medium (30-60 ft), 3=Large (> 60 ft).

Identify Input Parameters
4 parameters
Failure Likelihood = 2, Target Value = 2, Impact Severity = 2, Tree Size = 2 = 4 input(s) provided
Calculate Risk Rating
4 = 4
Calculate Category
1 = 1
Calculate Inspection Every
Inspection Every
36 = 36

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