If your task is small, then it's OK, since you know very well what are the requirements. But on related to what kind of work I do, that's a no go. You see I don

If your task is small, then it's OK, since you know very well what are the requirements. But on related to what kind of work I do, that's a no go. You see I don't do small tasks, I do full blown solutions. And on those an estimate can be as off as 100%. And usually, because clients wants this and that, it goes on like 300% in the end. Why? Because as time passes and new versions of solutions get on their hands, while they use it, they want some things to behave differently while some other things that didn't exists came to be implemented (change requests and new features). You see, I do your kind of work, meaning small tasks, after the solution is finished and it enters maintenance phase. Client comes back and, for example, on top of exporting to PDF, now he wants the same reports to be exported to Excel as well. Small task, to which I can give a very precise estimate in hours and after clients agrees to it, I go implement it. Usually that kind of task is around 100% accurate from estimation point of view.