Tool
Build Scope Estimator
Scope estimates go wrong on the component count, not the hourly figure. This makes the count explicit and shows what one page costs in weeks.
Run it
Build Scope Estimator
Method
Components, not pages
Pages are easy to count and tell you little. Components - the distinct things that have to be built and then made to work together - are what the hours attach to.
Method
Revision as a fraction
First build is not finished work. The allowance is entered as a fraction of the build rather than assumed, because how much revision a project needs depends on how settled the requirements were.
The honest part
Estimates are ranges pretending to be numbers
A single figure from clean inputs will still be wrong. Run it twice, once optimistically and once not, and treat the two results as the range you are actually working in.
Asked often
Common questions
What counts as a component?
Anything you would build and test on its own - a form, a table, a chart, a navigation bar. If it could break independently, count it.
Is the revision allowance a percentage?
It is a fraction: 0.4 adds forty per cent. Enter it as a decimal so the arithmetic stays visible.
Why report what one page costs in weeks?
Because scope conversations are easier when a cut has a price attached, and the price is time rather than a feature list.