Scope creep is rate erosion hidden inside a fixed price
A fixed project fee does not become harmless when work expands. The same revenue is spread across more hours, reducing the effective rate. Compare the revised rate with the internal hourly floor that funds your annual plan.
Two change-order numbers are useful. The minimum change restores the internal floor. The larger preserve-rate change keeps the original contracted effective rate on the added work. They answer different questions and should remain visible during a client conversation.
Scope ledger
Measure fee erosion
Enter approved change revenue separately from requested extra hours.
Worked example: 12 extra hours cross the floor
A $7,200 project estimated at 64 hours begins at an effective $112.50 per hour. Twelve additional hours bring total effort to 76. With no approved change order, the revised rate falls to $94.74, which is $5.26 below a $100 internal floor.
A $400 change order raises total revenue to $7,600 and restores the floor across 76 hours. A $1,350 change order prices the 12 new hours at the original $112.50 contracted rate. After $400 is approved, the tool shows $0 still needed for the floor and $950 still needed for the original rate. These are additional amounts, not cumulative change-order totals. The $1,200 value of added labor at the floor sits between the original commercial positions.
- Original effective rate
$7,200 / 64 = $112.50/hrThe fixed fee starts with 12.5% space above the floor.
- Revised effective rate
$7,200 / 76 = $94.74/hrUnpaid scope consumes the original pricing space.
- Restore the floor
76 x $100 - $7,200 = $400This is the smallest modeled repair before any change has been approved; remaining amounts subtract approved change orders and round upward.
Identify scope change by obligation, not by difficulty
Scope changes include new deliverables, new audiences, additional revision rounds, altered source materials, extra integrations, expanded stakeholder review, shortened deadlines, or responsibilities the original agreement did not assign. A task can be easy and still be outside scope.
Estimate the full added effort, including clarification, coordination, testing, handoff, and disruption to scheduled work. Logging only visible production time understates the change and makes the effective-rate comparison unreliable.
Write what changed, why it changed, the hours and direct costs affected, the schedule consequence, and the approved price. A clear record protects both parties from relying on memory.
Free changes need an explicit budget
You may intentionally absorb a small correction, relationship gesture, or mistake you caused. Name the reason and record the hours. Otherwise repeated exceptions become invisible operating costs and weaken future estimates.
This calculator does not interpret a contract, decide whether a request is legally in scope, or draft a change clause. It assumes the entered hours are additional and the internal floor is current. Discuss contract questions with a qualified professional in your jurisdiction.