Use internal delivery cost
Revenue and billable rates do not measure delivery cost. Use a realistic internal hourly cost that includes the people and overhead required to finish the work.
Topic center
Fixed-price project margin
Fixed-price project margin depends on the fee staying fixed while delivery cost changes with time, contractors, revisions, and scope. Teams should estimate profit before work starts, update the forecast with actual hours, and calculate the remaining safe hours before agreeing to additional work.
Decision model
Start with the calculation, then test the assumptions.
projected profit = fixed fee - external costs - ((hours used + forecast remaining hours) x internal hourly cost) Safe additional hours are the hours that can still be used before projected profit falls below the chosen target. A negative result means the project is already under the target assumption.
Practical checks
3 checks before relying on the resultForecast remaining work
Actual hours explain the past, but margin decisions also need an estimate of the hours and external costs still required to complete the agreed scope.
Document scope decisions
Requests that affect deliverables, timeline, revision count, or margin should receive written clarification before the team starts the additional work.
Recommended reading
Guides reviewed for this workflow.
Client project margin How Many Extra Hours Can a Project Absorb?
A method for calculating how much additional work a fixed-price project can absorb before margin becomes unsafe.
Reviewed 2026-07-23 Client project margin How to Calculate Profit on a Fixed-Price ProjectA practical guide for freelancers and agencies calculating profit on fixed-price client work.
Reviewed 2026-07-23 Client project margin When to Send a Scope Change Approval EmailHow freelancers and agencies can decide when a client request needs written scope approval.
Reviewed 2026-07-23Limits and source checks
A margin model is only as reliable as its hourly-cost and remaining-work assumptions. Update both when staffing or delivery conditions change.
Written approval emails support project operations but do not replace a contract amendment or legal review when the agreement requires one.