See how much of your MRR rides on your biggest customers. Get a risk rating against published due-diligence thresholds, and the impact if your largest account churns.
All monthly recurring revenue, normalised.
Your single biggest account.
Optional. Includes the largest customer.
Optional. Includes the top 5.
Used to estimate how long it takes to regrow lost MRR if your largest customer churns.
The dashed lines mark the 10% single-customer disclosure trigger (ASC 280) and Wall Street Prep's 25% top-5 red flag.
Concentration % = top-N MRR ÷ total MRR × 100 Computed for your top 1, top 5 and top 10 customers. The figures are combined, not exclusive bands: the top 5 includes the top 1, and the top 10 includes the top 5. If you have fewer than 5 or 10 customers, that field simply equals total MRR and concentration is 100%.
ARR at risk = largest customer's MRR × 12 The MRR lost if your largest customer churns is, by definition, the same percentage as their concentration. Losing a 15% customer wipes out 15% of MRR overnight.
Months to regrow = ln(total ÷ remaining) ÷ ln(1 + g) Where g is your monthly net MRR growth rate as a decimal. It answers how long it takes to get back to today's MRR after the loss. If growth is zero, the answer is never at the current rate. If the whale was your entire MRR, there is nothing left to compound from.
The bands are anchored to published lines, and the worst band wins. The 10% single-customer line is both the US GAAP major-customer disclosure trigger (ASC 280-10-50-42) and Wall Street Prep's red-flag rule. Top-5 above 25% is Wall Street Prep's second red flag. And 15-20% of ARR from one customer is FE International's must-be-priced-into-the-deal band.
The Low to Critical grading built on top of those published lines is our own, so treat the label as a summary rather than an official standard. The top-10 figure has no published threshold; it is shown as context only and never affects the rating.
Concentration thresholds get quoted loosely. These are the specific published sources this calculator grades against, each verified at the source.
| Threshold | What it means | Source |
|---|---|---|
| 10% from one customer | US GAAP disclosure trigger: public companies must disclose the fact and the amount whenever a single external customer reaches 10% or more of total revenues. Entities under common control count as one customer. | ASC 280-10-50-42, via Deloitte DART Segment Reporting roadmap (2025) |
| 10% top-1 / 25% top-5 | Analyst rule of thumb: one customer above 10% of revenue, or the top five above 25%, are deemed potential red flags. Materiality still depends on the customer relationships and the industry. | Wall Street Prep, Customer Concentration Risk (2025) |
| 15-20% of ARR from one customer | In SaaS acquisition due diligence, a single customer above 15-20% of ARR is a risk factor that needs to be priced into the deal. At 25% from one client, especially with a change-of-control clause, it affects both valuation and deal structure. | FE International, SaaS Due Diligence Checklist for Buyers (2026) |
| Low concentration = higher ARR quality | Low customer concentration makes ARR more stable because no single customer can materially impact revenue. Concentration is a consideration for most buyers when they assess the quality of a SaaS company's ARR. | Software Equity Group, ARR and Its Impact on Valuation (2025) |
Customer concentration risk is the danger that too much of your revenue depends on too few customers, so losing one account materially damages the business. It is normally measured as the percentage of total revenue (or MRR) coming from your largest customer and from your top 5 or top 10 combined. The higher those percentages, the more fragile your revenue base looks to lenders, investors and acquirers.
Divide the revenue from a customer (or group of top customers) by total revenue and multiply by 100. For a Stripe-based SaaS, use normalised MRR: if your biggest customer pays $6,000 of $40,000 total MRR, concentration is 6,000 ÷ 40,000 × 100 = 15%. Repeat for your top 5 and top 10 combined to see the full picture.
The most widely used line is 10%: US GAAP (ASC 280) requires public companies to disclose any single customer at 10% or more of revenue, and analysts such as Wall Street Prep treat anything above it as a potential red flag. FE International's due-diligence guidance says a single customer above 15-20% of ARR must be priced into an acquisition deal. Below 10% is generally considered healthy.
Wall Street Prep's rule of thumb is that the top five customers contributing more than 25% of total revenue is a potential red flag, so staying under 25% is a sensible target. Context matters: an enterprise SaaS with a handful of large contracts will naturally run higher than a self-serve product with thousands of small subscriptions.
Yes. Software Equity Group notes that low customer concentration makes ARR more stable, and that concentration is a consideration for most buyers assessing ARR quality. FE International's 2026 due-diligence checklist says a customer above 15-20% of ARR is a risk factor that gets priced into the deal, through a lower multiple, earnouts tied to retention, or restructured terms.
Grow the rest of the base faster than the whale: broaden acquisition channels, add lower-tier pricing to widen the funnel, and expand into adjacent segments so new revenue dilutes the big account's share. Defensively, secure longer contracts with your largest customers and deepen product integration. Concentration falls naturally as long as your top account grows more slowly than total MRR.
Not at an early stage. Most B2B SaaS companies start with one or two anchor customers, and a large committed customer can fund product development. It becomes a problem when it persists as you scale, because diligence teams model the loss of your top account and discount accordingly. The goal is a downward trend: each quarter, your largest customer should be a smaller share of MRR than the quarter before.
Public companies reporting under US GAAP do: ASC 280-10-50-42 requires disclosure of the fact and the revenue amount for any single customer at 10% or more of total revenues, though the customer need not be named. Private SaaS companies have no such obligation, but acquirers and lenders will ask for a customer-by-revenue breakdown in due diligence anyway, which is why the same 10% line is the informal benchmark.
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