Customer Revenue Concentration: The Median Contractor Gets 31.6% From One Client

The Median Contractor Is Already in the Danger Zone

The median contractor gets 31.6% of all revenue from a single customer.

That number comes from analyzing 959 contractors with at least $100K in annual revenue across the BuildOps dataset — HVAC, plumbing, electrical, mechanical, and refrigeration. Not a survey. Not a sample. Actual invoicing data.

Here's why 31.6% matters: PE buyers, lenders, and bonding companies all have thresholds for customer concentration risk. The median contractor in our dataset already exceeds every one of them.

The Full Distribution

The average is worse than the median: 39.8% from a single customer. That's pulled up by the extreme cases — contractors at P90 get 88.7% from one client. Their top 5 customers account for 100% of revenue. No other customers exist in any meaningful sense.

Even the median is alarming. When your largest customer represents nearly a third of revenue, every decision they make — to switch vendors, bring work in-house, reduce scope, or delay payment — directly threatens the viability of your business.

We've written about customer profitability analysis and why your biggest client by revenue may not be your most profitable. Concentration makes that problem worse: when an unprofitable customer is also a third of your revenue, you can't reprice them without risking the whole business.

What PE Buyers See

I spent two years in private equity evaluating contractor acquisitions. Customer concentration was the first thing we flagged — before margins, before EBITDA quality, before financial infrastructure. Here's the framework every PE firm uses:

The median contractor in our dataset — at 31.6% — is already in deal killer territory. Not the outliers. The middle of the distribution. The average contractor at 39.8% is in "enormous risk" territory.

I've covered the full PE evaluation framework in a separate post, but here's the valuation math on concentration specifically: a well-diversified contractor might command 5-6x EBITDA. The same business with 35% concentration? 3x EBITDA. That's a 40% valuation discount on the same revenue, the same margins, the same team.

For a $10M contractor running 15% EBITDA margins ($1.5M EBITDA), the difference between 5.5x and 3x is $3.75 million in enterprise value. That's the difference between a life-changing exit and a disappointing one.

This is also why revenue mix matters so much for valuation. Service-heavy contractors with diversified SA books tend to have lower concentration — dozens or hundreds of customers on recurring agreements. Install-heavy contractors tend to have 3-5 large clients driving the bulk of revenue. Same revenue, dramatically different risk profile and multiple.

The Lending Problem

PE isn't the only place concentration hurts. SBA lenders flag customer concentration at 25% — a single customer representing more than a quarter of revenue triggers additional scrutiny.

When lenders see concentration above 25%:

• Down payment requirements increase from the standard 10% to 15-20%
• Interest rates adjust upward for risk
• Loan-to-value ratios tighten
• Additional collateral or personal guarantees may be required

At the median concentration of 31.6%, more than half of all contractors in our dataset would face these tougher lending terms. If you're financing equipment, acquiring another contractor, or funding a facility expansion, your customer concentration is making that capital more expensive.

Bonding companies run the same analysis. High concentration means higher risk of revenue disruption, which means tighter bond lines. For commercial contractors who need bonding capacity to bid work, concentration directly limits your growth ceiling.

The Revenue Cliff Scenario

Forget valuations and lending for a moment. The operational risk is just as severe.

If the median contractor loses their top customer, they lose 31.6% of revenue overnight. For a $5M contractor, that's $1.58M gone. The overhead doesn't shrink proportionally — you still have the trucks, the office, the dispatcher, the insurance. Fixed costs don't flex with a revenue cliff.

At P90, losing the top customer means losing 88.7% of revenue. That's not a setback. That's a shutdown.

And it happens. Customers get acquired. Facility managers change. National accounts consolidate vendors. Property management companies switch to in-house maintenance. The customer doesn't need to be unhappy with you — they just need to change strategy.

The contractors who survive customer loss are the ones who had concentration below 15% before it happened. The ones at 30-40% who lose that customer are scrambling to cover payroll within 60 days.

The SA Power Law Makes It Worse

The service agreement data shows why concentration is so hard to fix: 1.4% of service agreements generate roughly 50% of SA revenue. The largest contracts — averaging $520K per agreement — are overwhelmingly concentrated in a handful of enterprise customers.

That creates a structural trap. Your biggest SA is with your most concentrated customer. Growing SA revenue means landing more of those large enterprise agreements. But each new large SA deepens concentration unless you're simultaneously growing the base of smaller accounts. Most contractors default to chasing the big contracts because the unit economics are better — and their concentration ratio creeps up year over year without anyone noticing.

How to Fix It

Customer concentration doesn't fix overnight. But the trajectory matters more than the current number — especially to PE buyers and lenders.

1. Know your number. Pull trailing 12-month revenue by customer. Calculate top 1, top 5, and top 10 as a percentage of total. If your top customer is above 20%, you have work to do.

2. Grow the denominator. The fastest path from 35% to 20% isn't dropping your biggest customer — it's growing revenue from other accounts. Account penetration and service agreement expansion with your next-tier customers shift the ratio without losing a dollar.

3. Diversify the pipeline. If your quote conversion rate is healthy but all your quotes come from the same 5 customers, conversion rate doesn't help. Track quote volume by customer to ensure new business development isn't just deepening existing concentration.

4. Track it quarterly. Add customer concentration to your weekly or monthly KPI dashboard. If the trend is moving in the wrong direction, catch it before it becomes a valuation haircut.

5. Mirror the analysis on the vendor side. Revenue concentration and vendor spend concentration are two sides of the same coin. The median contractor sends 33.1% of all spend to a single vendor. Dual concentration — one customer for revenue AND one supplier for materials — compounds the risk.

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The Bottom Line

The median contractor gets 31.6% of revenue from a single customer. That number already exceeds the thresholds used by PE buyers (>30% = deal killer), SBA lenders (>25% = tougher terms), and bonding companies to flag risk.

If you're building toward an exit, customer concentration could cost you 40% of your valuation — the difference between 5-6x EBITDA and 3x. If you're not planning to sell, it could cost you the business if that one customer walks.

The fix takes time, but starts with knowing the number.

Q: How does Level help with customer concentration risk? A: We build a customer concentration dashboard as part of every engagement — top 1, top 5, and top 10 customers as a percentage of trailing 12-month revenue, tracked quarterly. We identify the highest-risk relationships, model the revenue cliff scenario, and build a diversification plan targeting specific accounts for growth. If you're preparing for a PE process, we'll get your concentration to defensible levels before you go to market.

Q: What's a safe customer concentration level? A: Below 10% from your top customer is ideal and won't raise flags with any buyer or lender. Below 20% is manageable with the right story. Above 25% triggers scrutiny from SBA lenders. Above 30% is deal-killer territory for most PE buyers. The median contractor at 31.6% has work to do — but 12-24 months of focused diversification can move the number significantly.

Q: How do I reduce concentration without losing my biggest customer? A: You don't need to. The math works by growing the denominator — increasing revenue from other customers while maintaining the top account. Cross-selling into existing accounts, expanding service agreement coverage to new properties, and building pipeline with new customers all shift the ratio. A $5M contractor going from one customer at $1.58M (31.6%) to total revenue of $7M with that customer still at $1.58M brings concentration down to 22.6% — without losing a dollar from the relationship.