Methodology: Scope Creep Cost Calculator

1. Scope

Quantifies the opportunity cost of a project that ran over its scoped hours. Compares quoted price versus actual effort to expose the effective hourly rate. It does not prescribe change-order process.

2. Inputs and outputs

Inputs

quotedPrice number (currency)
quotedHours number
actualHours number
targetHourlyRate number (currency)

Outputs

effectiveHourlyRate

quotedPrice / actualHours.
hoursOverQuote

actualHours − quotedHours.
opportunityCost

hoursOverQuote × targetHourlyRate.

Engine source: src/lib/scope-creep-cost-calculator/engine.ts

3. Formula / scoring logic

effective_hourly  = quoted_price / actual_hours
hours_over        = max(0, actual_hours - quoted_hours)
opportunity_cost  = hours_over * target_hourly_rate

4. Assumptions

Target hourly rate is the user's opportunity-cost rate (what they could earn elsewhere for the same hour).
Actual hours captures all billable time including discovery and rework.

5. Data sources

This tool relies on user inputs and standard arithmetic; no external benchmark data is bundled. When a question depends on an industry reference (for example, typical churn rates or hourly-wage medians), the linked adjacent tools cite their primary sources on their own methodology pages.

6. Known limitations

Retrospective. Does not prevent scope creep; it makes the cost visible after the fact.
Ignores relationship value — a project run at a loss may still make sense if it leads to higher-margin follow-on work.

7. Reproducibility

Input
quotedPrice = $10,000, quotedHours = 80, actualHours = 120, targetRate = $150.

Expected output
effective_hourly ≈ $83.33, hours_over = 40, opportunity_cost = $6,000.

8. Change log

2026-04-24 methodology page first published.