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Probable Maximum Loss: Definition & Calculation

Updated: February 24, 2023

For insurance companies, the probable maximum loss is an important metric. 

There is such a thing as a worst-case scenario. And that’s when the probable maximum loss comes into play. But what exactly is PML? We’ll take a look in our handy guide.

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    • The maximum loss that an insurer is anticipated to suffer as a result of an insurance policy is known as the probable maximum loss (PML).
    • Insurers employ a variety of models and data to assess the risk involved in a policy’s underwriting, including the likely maximum loss (PML).
    • Each insurance provider has a unique definition and method for determining probable maximum loss (PML).
    • The following variables are taken into consideration while calculating probable maximum loss (PML): property value, risk factors, and risk mitigating variables.
    • The probable maximum loss (PML) is lower the more risk mitigating factors there are.

    What Is Probable Maximum Loss?

    The probable maximum loss (PML) is the absolute maximum loss that an insurance company can be expected to incur on any given insurance policy. It is a term that is most commonly associated with insurance policies for properties. This tends to be things such as flood insurance or fire insurance. 

    The probable maximum loss is regarded as the worst-case scenario for whoever the insurer is. This is under the assumption that there is no failure of existing safeguards. Common safeguards would be flood barriers or fire sprinklers. PML tends to be lower than the maximum foreseeable loss. Which is the potential damage if these safeguards fail to do their job. 

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    Probable Maximum Loss Assessment

    When assessing the risk involved in insuring a new insurance policy, insurance firms employ a wide range of data sets, including probable maximum loss (PML). This also aids in setting the premium that is to be paid. To determine the premium, insurers look at historical loss data for comparable risks, demographic and regional risk profiles, and data from the entire industry.

    An insurer would anticipate that a small percentage of the policies it underwrites may result in losses. But they would also know that the majority of them won’t. The expected maximum loss is one of many measures that helps calculate the amount of funds needed by an insurance business to ensure that it has adequate money to pay claims under policies.

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    How Do You Calculate Probable Maximum Loss?

    There are five main steps when calculating PML:

    1. Dollar value

    The first step is determining what the dollar value of the property is. You can then arrive at the potential loss financially if the entire property was destroyed. 

    2. Risk

    You then need to determine the risk factors that are most likely to cause an event that would lead to the loss or damage of the property. 

    3. Mitigation

    The next step is taking the factors that are risk-mitigating into account. These are any factors that can prevent major loss or damage. 

    4. Analysis

    You will then need to perform a risk analysis to figure out the likelihood that the risk-mitigating factors will reduce the probability of such an event occurring. 

    5. Calculation

    The final step is multiplying the value of the property by the expected loss percentage. The expected loss percentage is the difference between the risk-mitigating factors and the expected loss.


    For insurers, the probable maximum loss is an important aspect. This is especially true when considering the premiums of insuring property that has a risk of a major event happening to it. However, insurers will know that most of their insurance policies will never have any significant claim. This means that they can reliably make a regular profit and have enough spare capital to cover any significant losses.

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    FAQs on Probable Maximum Loss

    What Is the Difference Between Maximum Foreseeable Loss and Probable Maximum Loss?

    Probable maximum loss tends to be lower than the maximum foreseeable loss. This is because the MFL is the potential damage if these safeguards put in place to protect against major events fail to do their job.

    What Is Normal Probable Maximum Loss Expectancy?

    The normal loss expectancy assumes that all of the safeguards worked correctly, and the damage is limited to 10% of the insured value of the property.

    What Is the Maximum Possible Loss From an Investment?

    The PML from an investment is the maximum percentage of risk that can be subject to a major loss at any given time.


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