Client Profitability Calculator

What this calculator does

A client looks profitable on a gross-margin basis when revenue exceeds direct costs. Whether the same client is profitable on a full-costing basis depends on what the operator's hours could otherwise have produced and what the support overhead of running the relationship costs. This calculator returns five interlocking figures from a single set of inputs: gross profit, gross margin, opportunity cost on the time spent, overhead allocation, and the true annual profit that remains after all three subtractions. The output lets a gross-margin-positive client and a full-costing-negative client be the same client — a pattern that's invisible without the per-client view.

How the math works

Gross profit is annual revenue minus direct costs: GP = R − C. Opportunity cost is monthly hours × 12 × the opportunity hourly rate: OpCost = H × 12 × O. Overhead cost is monthly overhead × 12: Overhead = M × 12. True profit is gross profit minus opportunity cost and overhead: P = GP − OpCost − Overhead. Gross profit per hour is gross profit divided by annual hours. The calculation assumes the entered figures are stable across the year and that the opportunity-cost rate reflects what the same hours could realistically have produced on the next-best alternative use, not an aspirational rate.

Worked example

A client paying 50,000 in annual revenue, with 15,000 in direct costs, 25 hours per month of operator time at a 100 opportunity hourly rate, and 500 in monthly overhead. Gross profit: 50,000 − 15,000 = 35,000 (a 70% gross margin). Opportunity cost: 25 × 12 × 100 = 30,000. Overhead cost: 500 × 12 = 6,000. True profit: 35,000 − 30,000 − 6,000 = −1,000. Gross profit per hour: 35,000 ÷ 300 = roughly 117. The client appears profitable on a gross basis with a healthy 70% margin, but produces a small loss on a fully-costed basis because the operator's hours could plausibly have generated similar value on alternative work without carrying the same support overhead. The pattern is common in professional services and is the reason gross-margin-only views can mislead about which clients actually contribute.

What moves the result

Four levers shape the outcome. The opportunity hourly rate is often the largest swing factor — entering a higher rate makes more clients look unprofitable on a fully-costed basis. Monthly hours scale opportunity cost linearly: doubling time on the client doubles the opportunity-cost line. Direct costs reduce gross profit and feed straight through to true profit. Monthly overhead applies a fixed annual subtraction independent of the other inputs. The revenue input scales gross profit and gross margin together but does not change the opportunity or overhead lines, so high-revenue clients with disproportionate time loads can still flip negative under full costing.

How to read the opportunity-cost figure

The opportunity cost is the value of the hours the client consumed valued at the next-best use of those hours. Setting the opportunity-cost rate equal to a freelancer's standard billable rate produces a strict view: any client paying less per hour than that rate looks unprofitable. Setting it equal to gross profit per hour across the rest of the book produces a relative view: clients are profitable if they meet or exceed average client economics. Setting it to a lower figure — for example a conservative wage rate — produces a forgiving view that mostly highlights only the clearly-bad clients. The figure is sensitive to this choice; running the calculator at two or three rates usually clarifies which clients are robustly profitable across all framings versus borderline at one specific rate.

What the calculator does not capture

The output is single-year and quantitative. It does not model relationship value beyond the current year (long contracts, referrals generated, learning), the portfolio value of recognisable client logos for credentials, payment timing and working-capital effects, collection risk, scope creep that erodes the effective hourly rate over time, learning curves that reduce future hours on the same engagement, or the operational friction of removing a client from the book. A complete relationship review usually combines this calculator's snapshot with a longer-horizon view and qualitative factors the snapshot does not surface.

Notes on the inputs

Excluding non-billed time from the hours input understates opportunity cost — communication, revisions, scoping, and project administration are real consumed hours even when not invoiced. Choosing an opportunity rate too low makes most clients look profitable, including some that are not. Treating overhead as zero produces a clean gross-profit view with no full-costing component. Using a single best-month figure for any input rather than an averaged figure produces a snapshot that does not generalise across the year.