I am 20 years in development business now.
This simple rule of thumb works for me and the team:
(Your honest and concise estimation) * 3
There are just to many unknowns you cannot foresee. Software development is complex.
There are just to many unknowns you cannot foresee. Software development is complex.
e.g. say you think it will take a day, so 2 days, 4 days, add another day, likely estimate is 5 days.
My pet theory is that when we estimate, we typically think of how long it will take to figure out a working solution to the problem, but forget about how long it takes to debug it, add tests, rework for changed requirements and unexpected nuances, and then roll it out and do any training, etc.
I make the most optimistic prediction and then * PI.
The part you didn't mention is that for most businesses it's better to be over than under in the estimation. I also explain this thought process to the various stake holders. We can certainly try to tighten up an estimate, but that runs a higher risk of being under which is usually a worse outcome (promised launch dates are missed, marketing is missed/happening, customers are told, etc...).