Tolerable Risk Level — A Critical Concept in Risk Analysis

Risk assessment is not about calculating numbers. It is about knowing when risk becomes unacceptable. Without a defined tolerable risk level, risk analysis has no real meaning.

Why Tolerable Risk Matters

The most vital aspect is understanding what your tolerable risk level is.

Establishing risk by itself is not so attractive. You can express risk as very high, 1000 or red. It does not matter that much.

What is much more important is whether you know when your risk is too high. A risk of 1000 sounds high, but if your tolerable risk level is 10000, it is low. Not knowing your tolerable risk is the worst thing.

The key question is: at what point does risk become unacceptable for your organization?

Risk Numbers Without Context Are Meaningless

Risk values on their own do not tell you what to do. Whether you use numbers, colours, or categories, the value only becomes meaningful when it is compared to a limit.

A risk score of 1000 may look alarming, but without context, it does not drive action. Only when you compare it against a defined tolerable risk level can you decide whether mitigation is required.

Tolerable Risk Drives Decisions

The real purpose of risk assessment is decision-making. Should you reduce the risk, accept it, or redesign the system? These decisions depend entirely on your tolerable risk level.

If the tolerable risk level is not defined, then every risk assessment becomes subjective. Different people will interpret the same result differently, leading to inconsistent and often ineffective decisions.

Personal vs Organisational Risk Tolerance

How much risk you can tolerate is a personal issue. Understanding your tolerable risk applies to people as well as to companies.

Individuals often make decisions based on intuition, experience, or personal comfort with risk. Organisations, however, must define tolerable risk in a structured and consistent way, often based on regulations, industry standards, and business objectives.

Why It Is Often Overlooked

Tolerable risk is the one aspect of risk analysis that is often overlooked in business. Many organisations focus heavily on identifying hazards and calculating risks but fail to define what is acceptable.

This creates a gap between analysis and action. You may have detailed risk studies, but no clear basis for deciding what needs to be done.

The Impact on Functional Safety

In functional safety, tolerable risk is fundamental. It determines the required risk reduction and therefore the required Safety Integrity Level (SIL).

If the tolerable risk is set too high, you may under-design your safety functions. If it is set too low, you may over-engineer solutions and introduce unnecessary cost and complexity.

Practical Takeaway

Before performing any risk assessment, make sure that the tolerable risk level is clearly defined and agreed upon. This ensures that the results of the analysis can be translated into clear, consistent, and justifiable actions.

It is the one aspect that makes a massive difference in the results, and a significant difference in what you will do with the results or not.