The Math Behind the Map
We don't use fear-mongering or anecdotal evidence. Our DisasterCalculator Risk Score is built directly on the FEMA National Risk Index, a dataset that calculates the annualized frequency, exposure, and loss ratio for 18 natural hazards.
Our Core Philosophy: Rational Preparedness
Most disaster advice is emotional, relying on scary anecdotes to sell products.DisasterCalculator.com is different. We believe that preparation should be based on probability, not panic.
How We Calculate Risk
Our primary data source is the FEMA National Risk Index (NRI). This comprehensive dataset evaluates 18 natural hazards across every US county.
The Risk Equation
1. Frequency
How often does it happen? We analyze historical data (e.g., hurricane strikes over 100 years) and future climate projections to determine probability.
2. Exposure
What is in the path? This accounts for population density, property value, and agriculture. A storm hitting a city has higher exposure than one hitting an empty field.
3. Vulnerability
How susceptible is the community? We look at social factors like age, income, and vehicle access. Communities with fewer resources struggle more to recover.
4. Resilience
How well can they bounce back? High-quality infrastructure, hospital capacity, and strong emergency services lower the total risk score.
The "Exponential Risk" Scaling
Most cities in the US have some level of risk, meaning a linear scale (0-100) often bunches everyone at the top. To make the data more useful, we apply an exponential scaling factor to our final scores.
This means the difference between a 99 and a 90 is massive. A score of 90 doesn't mean "safe"—it means "significantly safer than the absolute worst-case scenario." This curve helps highlight the extreme outliers that require the most urgent preparation.
Interpreting the "Risk Score"
FEMA provides raw values that can be abstract. To make this data actionable, we normalize these values into a simple 0-100 Risk Score.
- 0-20 (Very Low): Minimal historical activity and high community resilience.
- 21-40 (Low): Occasional minor events, but generally safe.
- 41-60 (Moderate): Regular exposure to at least one major hazard type.
- 61-80 (High): Significant history of major events (e.g., coastal hurricane zones).
- 81-100 (Very High): Extreme exposure to multiple compounding hazards (e.g., earthquake + wildfire zones).