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Free customer concentration checker

What happens if your biggest customer leaves?

Get a free, educational concentration risk check in around 30 seconds. Two numbers, one straight answer.

  • Free
  • No account needed
  • No bank connection

How we work it out

Same as the runway calculator — simple arithmetic, not a benchmarked score, so it works for any small business. Here's what happens:

  1. Your total revenue

    Everything the business brought in over the last 12 months.

  2. Revenue from your single biggest customer

    Just the one — whichever customer accounts for the most.

  3. What share that customer represents

    Compared against the general danger zones cited across business risk and M&A guidance — under 10% is diversified, 30%+ is a real concentration risk.

Question 1 of 3

Everything the business brought in, from all customers combined.

Just the one customer — whichever accounts for the most, over the same 12 months.

Are these numbers from your real books, or a rough estimate?

Estimated numbers can still get a useful result — it just won't be shown as fully healthy (green), since we can't be that confident in a guess.

Your result is ready.

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Your concentration risk

0%

Numbers change — come back anytime and run this again with the same email and business name, and we'll update your concentration check to the latest result.

Your Profit Lights

This calculator provides an educational estimate only and does not provide certified financial, accounting, or business advice. It only looks at revenue share — not contract terms, relationship strength, or how easily that revenue could be replaced. Actual risk depends on more than one number.

Want this tracked automatically instead of checking by hand? Tell me at michael@profitlights.com — I'm exploring it.