Why estimate the project in Story points, a note to clients
No project can go very long before someone starts asking “When will you be done?” The best approach for estimating stories would be one that: • allows us to change our mind whenever we have new information about a story • works for both epics and smaller stories • doesn’t take a lot of time • provides useful information about our progress and the work remaining • is tolerant of imprecision in the estimates • can be used to plan releases An approach that satisfies each of these goals is to estimate in story points. A nice feature of story points is that each team defines them as they see fit. Source - Mike Cohn's book