SLE (Single Loss Expectancy)
Definition
The expected monetary loss from a single occurrence of a specific threat event against a specific asset. Calculated as: SLE = Asset Value x Exposure Factor, where the exposure factor is the percentage of asset value lost in the event.
- Formula
- SLE = Asset Value x Exposure Factor
- Exposure factor meaning
- Percentage of asset value lost in one event
- Scope
- A single occurrence of a specific threat
- Related metric
- ALE, which multiplies SLE by annual occurrence rate
Common questions
How does SLE relate to ALE?+
SLE estimates the loss from one occurrence of a threat event, while Annualized Loss Expectancy multiplies that SLE by the estimated annual rate of occurrence to project expected yearly loss.
Why use an exposure factor instead of the full asset value?+
A single incident rarely destroys an entire asset's value, so the exposure factor scales the loss estimate to a realistic proportion rather than assuming total loss every time.
Related terms
- ALE (Annualised Loss Expectancy)
- The expected monetary loss from a specific threat over a one-year period. Calculated as: ALE = SLE x ARO (Annualised Rate of...
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