Calculator
The fastest scope creep calculator is your hourly rate times the favor you almost said yes to.
If a client asks for 12 hours of extra website work at $125/hour, that is not a favor. It is a $1,500 change request.
Extra hours x your rate = additional investment.
Add timeline impact so the client sees the tradeoff.
Send approval before opening the next task.
Estimate the real work
Break the request into implementation, QA, communication, revisions, and launch time. Web changes usually hide more work than the first message suggests.
Price the change order
Multiply the estimated hours by your rate or set a flat fee. The important part is that the number is visible before the work starts.
Protect the delivery date
Extra work consumes calendar time. A good change order explains the new date so the client cannot expect more scope on the same deadline.
Make approval easy
A clean approval packet is easier for the client than a tense email thread. They click approve, and both sides have the same record.