Customer Concentration Risk

Why this question matters

A business can have many customers and still depend heavily on one or two of them. That dependence matters when planning capacity, cash and commitments. This calculator measures the revenue share of the largest entered customer and the top three entered customers, then shows revenue after losing the largest. It makes exposure visible without pretending to know whether a customer will leave. The purpose is to prepare a proportionate response to concentration.

Use a consistent revenue period and enter the largest customers individually. The remaining customers can be combined in the other revenue field. That remaining group must not conceal a customer larger than those listed, otherwise the largest customer measure will be understated. Use anonymous labels. The calculation needs revenue amounts, not names, contact details or commercially sensitive contract information.

Decide what counts as one customer for your business. Several branches controlled by the same buying organisation may create a common exposure even if they have different invoice accounts. Conversely, independently owned buyers may not behave as one group. Document the grouping rule and apply it consistently. Where revenue is seasonal, compare an annual view with the period in which the business faces its largest commitments.

Understand the method

1. Largest customer share = largest customer revenue ÷ total revenue × 100.
2. Top three share = sum of the three largest entered customer revenues ÷ total revenue × 100.
3. Revenue after largest customer loss = total revenue − largest entered customer revenue.

Total revenue equals the sum of the entered customer rows plus other revenue. The largest customer share divides the highest entered customer revenue by that total. The top three share uses the three largest entered rows. Revenue after the largest customer loss subtracts that largest row from total revenue. The rows are sorted for calculation, so the order in which you entered them does not change the arithmetic.

Read concentration as exposure, not as a verdict on the relationship. A large customer may provide reliable demand, useful scale and prompt payment. The risk arises when commitments assume that the revenue will continue without considering alternatives. Examine contract timing, product dependence, receivables and the ability to reduce or redirect costs. A revenue loss does not translate into an equal profit loss because some delivery costs may also change.

Prepare a scenario for the largest relationship. Estimate the cash effect if orders reduce, payment is delayed or the contract ends at an agreed date. Identify which costs continue and how long replacement demand might take to develop. Then consider a proportionate diversification plan without neglecting the existing customer. Winning many small customers at poor contribution can reduce concentration while weakening the business in another way.

Keep the result in perspective

This is a transparent planning calculation or self assessment, not a sector benchmark, professional valuation or a prediction of an outcome.

Enter the largest customers individually in order to interpret concentration correctly. The unlisted group must not contain a customer larger than those entered. This measures revenue exposure, not the probability of losing a customer.

The calculator does not estimate default probability, customer retention or the legal enforceability of a contract. It also does not examine customer profitability. A high share is a reason to understand dependence, not a universal instruction to reject large orders. There is no sector specific safe concentration threshold supplied by the tool.

At least one revenue amount must be positive. If only one or two customers are entered, the top three result covers those entered rows and does not reconstruct the customers hidden in other revenue. Check that the individually entered rows really are the largest. The displayed loss scenario is based on revenue and excludes changes in cost, cash timing and the response of other customers.

Read the full limitations or explore how Ayodeji approaches this work.