In 2011, a single semiconductor fabrication plant in Japan was flooded by the Tōhoku tsunami. Within three months, automotive production lines on three continents had halted — not because those manufacturers had any direct exposure to Japan, but because their Tier-2 suppliers did. The rupee cost of single-source dependency is not theoretical. It is a number you can calculate before the disaster occurs.

Why Single-Source Risk Is Systematically Underpriced

Procurement teams make single-source decisions for rational reasons: volume leverage, supplier investment in tooling, qualification cost, and speed. The problem is not the decision — it is the arithmetic that follows. When probability of disruption is low, its multiplication against impact produces a number small enough to ignore in a budget review. Until the event occurs. At which point the number is no longer theoretical.

The Expected Annual Loss (EAL) framework forces this calculation to occur before commitment. EAL = Probability × Impact. If a supplier has a 15% annual probability of failing to deliver, and a disruption costs ₹28 lakhs in revenue loss and emergency sourcing, the expected annual loss is ₹4.2 lakhs. That is the correct risk-adjusted annual cost of not dual-sourcing — and it is a number that belongs in a category spend analysis.

“The cost of single-source dependency is always calculable before the failure. The only question is whether anyone ran the arithmetic before signing the contract.”

The Three Inputs That Determine Risk Score

Probability of disruption is the most contested input — and the most important. Financial stability, geographic distance, geopolitical exposure, and supplier concentration all feed into it. A supplier with a current ratio below 1.0 and a single manufacturing site in a high-risk geography is not a 5% probability event. Run the Supplier Financial Health Radar alongside this calculator for a defensible probability figure.

Impact is the product of daily revenue at risk and disruption duration, plus the emergency sourcing premium applied to annual spend. The emergency premium — the percentage above normal cost you’ll pay for urgent alternate sourcing — is typically 20–50% for commodity materials and 80–200% for specialised or certified inputs. If no alternate source exists, model impact as full revenue loss for the duration.

The Switch Cost Comparison

The final output of this calculator compares Expected Annual Loss against switching cost — the one-time cost to qualify an alternative supplier. This comparison answers the only question that matters: is the annual risk cost higher than the cost to eliminate it? In most cases where single-source dependency has been allowed to persist for more than two years, EAL significantly exceeds the qualification investment. The arithmetic has been available throughout. Nobody ran it.

Using the Score in Practice

A risk score above 60 warrants immediate dual-source qualification. Between 40 and 60, formal mitigation planning and increased safety stock are the minimum response. Below 40, document the risk and review annually. The score is not a regulatory requirement — it is a decision tool. Its value is in making the conversation with operations and finance evidence-based rather than intuitive.