WhenMath

Deadlines & Project Capacity

This category is where a date stops being a single point and starts being a plan. Given a deadline and an amount of work, when does work actually need to start. Given a start date and a list of phases, where does each phase land. Given a fixed team size and a required weekly output, is the deadline even achievable. These questions share one underlying structure, a relationship between a start, a duration, an effort or capacity figure, and an end point, where any two known values should let you solve for a third.

A deadline is rarely just "count backward"

Working backward from a deadline has to account for the same conventions as working forward, which days count as working days, what buffer sits between "done" and "due," and whether a blackout date or a review phase sits inside the window and eats into it. A naive subtraction that ignores weekends, holidays, or a known review cycle produces a start date that looks fine and is quietly wrong.

Sensitivity is the point, not decoration

A deadline plan is only as good as its weakest assumption. Where a build phase runs one day long, or a buffer shrinks by a day, or weekly capacity drops by a few hours, the question that matters is what that does to the finish date, and which phase is actually the bottleneck. That kind of stress-test is meaningful here because the underlying model is a real dependency chain, not a single formula.

Where to go next

For the working-day mechanics a deadline plan relies on, see Business Days & Work Calendar. For a deadline anchored to a specific local time in a specific place, see Time Zones & Meetings.

Deadlines & Project Capacity tools