Customer Concentration Risk Calculator
Measure revenue concentration across your top customers using share and Herfindahl index, and assess the revenue at risk from losing a key account.
⚠️ Financial Analysis📐 Top-N share = Σ top customer revenue / total revenue; HHI = Σ(share²)💼 Business
Total annual revenue
Largest customer revenue
2nd largest customer
3rd largest customer
4th largest customer
5th largest customer
Gross margin (%)
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| Customer Concentration Risk Calculator | — | Top-N share = Σ top customer revenue / total revenue; HHI = Σ(share²) | percent and index |
Step-by-Step Examples
Example 1
High Concentration
Total 4,800,000; customers of 1,450,000 / 720,000 / 410,000 / 290,000 / 215,000; 42% margin.
- Largest = 1,450,000 / 4,800,000 = 30.2%
- Top 5 combined = 3,085,000 = 64.3%
- Losing the largest removes 1,450,000 revenue and 609,000 gross profit
- Above the 20% threshold buyers typically flag
✓ 30.2% largest — high concentration
Example 2
Well Distributed
Total 4,800,000; largest 384,000, others below that.
- Largest = 8.0%
- No single customer represents material risk
- Revenue base is resilient to individual losses
✓ 8.0% largest — low concentration
Example 3
Moderate
Total 3,000,000; largest 540,000 (18%), top 5 totalling 1,500,000 (50%).
- Largest customer 18% — moderate band
- Top 5 at 50% means half of revenue rests with five relationships
- Worth active diversification
✓ 18.0% — moderate concentration
Real-World Applications
Valuation Impact
Acquirers routinely discount valuations for customer concentration, since the risk transfers with the business.
Lending Assessment
Lenders treat concentrated revenue as elevated credit risk, which can affect facility size and covenants.
Negotiating Position
A customer representing a large revenue share holds substantial leverage in pricing and terms negotiations.
Diversification Target
Quantifying concentration turns diversification from a vague goal into a measurable objective.
Common Mistakes to Avoid
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Measuring concentration by customer count alone
Having many customers means little if a handful generate most revenue. Share of revenue is what matters, not the count.
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Overlooking related entities
Separate accounts belonging to the same parent group should be aggregated. Treating them separately understates true concentration.
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Ignoring concentration until an exit
Reducing concentration takes years of deliberate diversification. Discovering it during due diligence is far too late to fix.
Frequently Asked Questions
What is customer concentration risk? ▾
The risk that losing one or a few major customers would materially damage the business, measured by their share of total revenue.
What concentration level is concerning? ▾
A single customer above 20% of revenue is commonly flagged by buyers and lenders. Above 30% is generally treated as high risk.
How does concentration affect business valuation? ▾
Acquirers typically apply a discount, since the risk transfers with the business. Severe concentration can make a business difficult to sell at all.
Should related accounts be combined? ▾
Yes. Subsidiaries or divisions of the same parent should be aggregated, since a decision at group level affects all of them simultaneously.
How do I reduce concentration? ▾
Deliberate diversification of the customer base over time. It is a multi-year effort, which is why it should be addressed well before any exit process.