Dr. Paul Borosky, DBA, MBA
Business Consultant & Author
Guide 5 of 11 · Make Money
How to Calculate Customer Profitability
Your biggest customer is not always your best customer.
Every growing business ends up with one account it cannot imagine losing. Owners protect it, discount for it, and build the schedule around it. Revenue is only one of three things a customer brings you. The other two are how much you keep and how long you wait to get it.
Last Updated: 10/27/2026 · Written by Dr. Paul Borosky, DBA, MBA
The Short Answer
What Is Customer Profitability?
Textbook Definition
Customer profitability is the profit a customer generates after the direct costs of serving them, often adjusted for the cost of the working capital tied up in their receivables and the extra service time they require.
In Plain English
What a customer actually leaves you. Start with the gross profit on their work. Then ask how long they take to pay and how much of your time they eat. A big account that pays slowly and keeps the least may cost more than it looks.
Gross Profit per Customer
Revenue × Gross Profit Margin
Harbor Point: $71,900
Cash Tied Up in Waiting
(Revenue ÷ 365) × Days to Pay
Harbor Point: about $28,600
Show the Math
Ridgeline’s Customer Scorecard
Year 3 plan for Ridgeline Landscaping. Harbor Point is three condo properties, snow included. Residential is about 130 homes.
| Customer | Revenue | Margin | Gross profit | Days to pay | Hassle |
|---|---|---|---|---|---|
| Harbor Point | $232,000 | 31% | $71,900 | 45 | Medium |
| Residential | $220,000 | 46% | $101,200 | 12 | Low |
| Cleanups | $70,000 | 55% | $38,500 | 10 | Low |
| Installs | $70,000 | 53% | $37,100 | 5 | Medium |
| Other commercial | $48,000 | 42% | $20,200 | 38 | Low |
| Total | $640,000 | 42% | $268,900 |
Fictional, from the book. Gross profit rounded to the nearest $100.
The Method
How to Score Your Customers in 5 Steps
List your top customers by revenue.
Five is enough. Group small ones if you have hundreds.
Add margin and gross profit.
Revenue times the gross profit margin on that customer’s work. Rank by gross profit, not revenue.
Add days to pay.
Turn it into dollars: revenue divided by 365, times days to pay. That is the cash you are lending them.
Check concentration.
Divide your biggest customer’s revenue by total revenue. Many lenders and buyers get nervous above 20% to 30%.
Decide: grow, reprice, change terms, or let go.
Grow the customers who keep the most and pay the fastest. Reprice at renewal, add deposits, or shorten terms for the rest.
What If the Biggest One Leaves?
Harbor Point’s gross profit is $71,900. Ridgeline’s whole net profit plan for Year 3 is about $73,000. Lose the customer, and the year’s profit goes with it, because the yard, the insurance, the loan payments, and the crew all stay. A customer who is a third of your revenue owns a third of your business.
Two Owners, Same Town
Mike Capped His Biggest Account. Dale Built His Season Around One.
Mike set a rule: no customer over 30% of revenue within two years. Harbor Point does not shrink. Everything else grows around it. Four new installs pushed planned revenue to $680,000, and Harbor Point’s share fell from 36% to 34%.
Dale’s biggest account, a property company with six apartment buildings, was 40% of his revenue. In February, the company was sold, and the new owners brought their own landscaper. By June, Dale had laid off two people and sold a mower for less than he owed on it. One account at 40% is not a customer. It is a boss.
Owner Warning
What Do Owners Get Wrong About Their Best Customers?
- Ranking customers by revenue instead of gross profit.
- Discounting the biggest account to keep it.
- Ignoring how long a big customer takes to pay.
- Letting one customer pass 30% of revenue.
- Never counting the hours a hard customer eats.
- Building the crew around a single contract.
From the Book
Who Owns Your Business?
Chapter 12 · Which Customers Make You Money
Dr. Paul’s Bottom Line
A customer who is a third of your revenue owns a third of your business.
Customer scorecards, concentration limits, and when to let a customer go. It is all in the book.
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Beyond the Book
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Customer Profitability Questions
How do you calculate customer profitability?
What is customer concentration risk?
Should I fire an unprofitable customer?
Keep Going
Related Guides
This guide is part of the small business finance guide.
Written by Dr. Paul Borosky, DBA, MBA, business consultant, author, and adjunct finance instructor with an MBA focused in finance.
This page is for general educational purposes only. It is not legal, financial, tax, accounting, or lending advice. Tax rules change by place and by year. Ridgeline Landscaping and its figures are a fictional illustration from the book, not a projection for your business. For decisions about your own business, consult a qualified professional.