We used to try and present estimates as a range ("between 5 and 10 weeks"), but we've settled for trying to provide a single number rather than a full span. Fo

We used to try and present estimates as a range ("between 5 and 10 weeks"), but we've settled for trying to provide a single number rather than a full span. For our time and materials estimates, we try to provide an ~85% confidence estimate, while for fixed bid projects we try to aim for a ~95% confidence estimate (and there's usually a pretty big gap between those two numbers, for the reasons pointed out in the article). So, in this scenario, we'd probably say to the client that it'll be done in about 8 weeks (making clear that's an estimate, and not a promise). One number, rather than a range, seems a lot easier to explain to a client and if you end up low (say it takes 3 weeks), then you have a pleasantly surprised client.