- Enter the annual trigger probability
Use the one-year probability for the exact parameter threshold in the policy.
- Choose a planning horizon
Enter the number of years over which you want at-least-one-trigger probability.
- Review cumulative probability
The main result shows the chance of one or more trigger-years over the horizon.
- Compare the no-trigger probability
This is the complementary probability that none of the years trigger.
- Use the independence assumption carefully
If hazard conditions are correlated or changing over time, use a more detailed model.
Parametric Insurance Loss Probability Calculator
This calculator estimates the probability that a parametric insurance trigger occurs at least once over a multi-year horizon. It converts an annual trigger probability into a cumulative probability, assuming each year has the same independent chance of triggering.
The calculation is useful for stress testing contract design, deciding how often a payout might occur over a planning period, or translating an annual hazard estimate into a longer-term view. It is not a catastrophe model: clustered events, changing hazard conditions, policy changes, and multiple triggers within one year are outside the simplified model.
Estimate cumulative trigger probability
%
years
Result
—
Probability of at least one trigger
At least one trigger—
No trigger over horizon—
Expected trigger-years—
Annual probability—
Formula:
P(at least one trigger in n years) = 1 − (1 − p)^nWhere:
- p: annual trigger probability as a decimal
- n: number of years in the planning horizon
Assumptions: Annual trigger events are treated as independent and the annual probability is assumed constant. The model counts whether a year triggers, not the number of events within a year.
What the result means
The percentage is the modeled chance that the selected trigger is reached in at least one year during the horizon.
Correlation between years or a changing hazard rate can materially change the result.
Given:
- Annual trigger probability: 8%
- Planning horizon: 5 years
Calculation:
No-trigger probability = (1 − 0.08)^5 = 0.6591. At-least-one probability = 1 − 0.6591 = 0.3409.
Result: Probability of at least one trigger: 34.09%.
Interpretation: An 8% annual chance does not simply become 40% over five years because the calculation accounts for the possibility of repeated no-trigger years.
Why is five times the annual probability not the exact five-year probability?
Adding annual probabilities double-counts scenarios in which more than one year triggers. The complement formula correctly calculates the chance of at least one trigger under the independence assumption.
Can I use a 100-year return period as a 1% annual probability?
That is a common approximation when the return period is defined as an annual exceedance probability of 1/100, but verify how the hazard source defines the return period.
What if annual probability changes each year?
Calculate the no-trigger probability as the product of each year’s individual no-trigger probability, then subtract that product from 1.
Does this estimate how many claims will occur?
No. The main result is the probability of at least one trigger-year. The expected number of trigger-years is shown separately as annual probability × years.
Can one year have multiple parametric payouts?
Some contracts can, subject to wording, aggregate limits, or reinstatements. This simplified model does not count multiple events within a year.