Chapter 12. Estimation
Base your story estimates on a similar story you've already done. This story will take about the same amount of time as a comparable story.
How do you come up with estimates? We've seen a lot of words devoted to this topic. We've seen quite a few mathematical formulae. The best of these are based on the lines of code yet to be written. These can tell you how much time it will take to develop so many thousand lines of code. This is particularly useful since it's so easy to estimate precisely how many lines of code a solution will require before you start writing it. (Spotted the sarcasm yet?)
Let's be clear, estimation is an art at best. You're not going to get accurate figures however hard you try. With a little bit of effort ...