Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Largest client share of revenue
34.3%
Top three client share
58.6%
Monthly revenue lost if they leave
$40,000
Months of runway after the loss
11.7
Annual revenue you'd need to replace
$480,000
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Got your number — what next?
Pick one, it takes 20 secondsHow to use this
- 1Enter annual revenue ($).
- 2Enter largest client's annual revenue ($).
- 3Enter top three clients' combined revenue ($).
- 4Enter monthly operating cost ($).
- 5Enter cash on hand ($).
- 6Read your largest client share of revenue on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Concentration risk is the quiet killer of profitable agencies: the margins look great right up until the account that funds 45% of payroll gives 30 days' notice. This calculator takes your total revenue and your top-client revenue, returns concentration percentage and a Herfindahl-style exposure read, then models the cash impact of losing that client — including how many months of runway remain and what replacement revenue you'd need to sign. Lenders and acquirers generally treat anything over 25% from one client as a material risk and discount valuation accordingly, so this number matters for exit value as well as sleep quality.
Worked example
Using the values the calculator loads with:
Inputs
- Annual revenue: 1400000 $
- Largest client's annual revenue: 480000 $
- Top three clients' combined revenue: 820000 $
- Monthly operating cost: 92000 $
- Cash on hand: 180000 $
Results
- Largest client share of revenue: 34.3%
- Top three client share: 58.6%
- Monthly revenue lost if they leave: $40,000.00
- Months of runway after the loss: 11.7
- Annual revenue you'd need to replace: $480,000.00
What each field means
Inputs
- Annual revenue ($)
- The annual revenue used in the calculation, measured in $. Starts at 1400000 $ so you have a working example on load.
- Largest client's annual revenue ($)
- The largest client's annual revenue used in the calculation, measured in $. Starts at 480000 $ so you have a working example on load.
- Top three clients' combined revenue ($)
- The top three clients' combined revenue used in the calculation, measured in $. Starts at 820000 $ so you have a working example on load.
- Monthly operating cost ($)
- The monthly operating cost used in the calculation, measured in $. Starts at 92000 $ so you have a working example on load.
- Cash on hand ($)
- The cash on hand used in the calculation, measured in $. Starts at 180000 $ so you have a working example on load.
Results
- Largest client share of revenue
- Returned as a percentage and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Top three client share
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Monthly revenue lost if they leave
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Months of runway after the loss
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual revenue you'd need to replace
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What concentration level is considered risky?
Above 25% from one client is the common threshold where lenders, insurers, and acquirers start applying a discount. Above 40% you are effectively a subsidiary of that client's marketing department, and their reorganisation becomes your restructuring.
Does a long contract reduce the risk?
It softens the timing, not the exposure. Most services contracts allow 30-90 day termination for convenience, so treat the notice period as your true buffer rather than the contract end date.
How fast can concentration realistically be reduced?
Usually by growing the rest of the book rather than shrinking the big account. Adding two mid-size clients a year against a flat anchor account typically moves concentration down 8-12 points annually — cutting the anchor instead just shrinks the business.
What does a runway of 999 mean?
It means the rest of your book already covers monthly operating cost, so losing the top client hurts profit but doesn't create a burn. That's the position you're aiming for.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
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Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Client Concentration Risk Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/agency-client-concentration
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/agency-client-concentration" target="_blank" rel="noopener">Client Concentration Risk Calculator — RevenueLab</a> (2026).</p>
Source: [Client Concentration Risk Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/agency-client-concentration) (2026).