When will it be done? When? When? WHEN??!!!!

[Oogiem]

How do I work out how long things will take and set reasonable and achievable deadlines.

Here is a formula I've used that is actually fairly accurate.

Estimating Times to do projects

Here's a good back-of-the-envelope estimate:

L = least possible time the project could take (most optimistic)
M = most likely time for the project to take (best guess)
W = worst case for time project could take (most pessimistic)

Obviously L < M < W

Estimated time = (L+3*M+W)/5

Then when I am setting a deadline that has monetary consequences (like to a boss or customer) I double that time.