We all have to do it at some point or other and it’s never easy. There is no magic formula, there is no way to find a truly accurate answer. All you can ever do is guess and suffer the consequences.
But there are a few things you can do to make that guess a little bit closer to the mark and there are only a few things you need to find out.
- What is the latest time the customer will allow you deliver?
- What is the minimum amount you can get away with?
- How much budget does the customer have?
Try and work these things out and build your estimate around them. Sure, build some sort of model to justify your numbers, maybe use something scientific looking like standard deviation and use fancy terminology like ‘risk budget’ and ‘contingency’ with percentages and things.
Ok, so you still want to try? Right then, on your own head be it, but here is some additional help in case you are still feeling misguided.
What does your gut feel tell you? Come on, your experience must tell you something? Is it 10 man days, 100, 1000? How long would it take you to do it, back when you were king/queen of code? Think of a number, you’ll probably be more right than you think.
Remember that when you are estimating for a project, you are unlikely to be able to pick-up and drop individuals as you go along the cycle of the project. Once you have them onboard, you will either have to keep them to the end, or risk losing them forever to another project, so best budget that way too.
Then to confirm this, use another method of quantification to check your figures. Maybe the obvious but often forgotten ‘bums on seats’ estimate. Count the number of people you have available to do the work, multiply that by your gut feel duration and that gives you a guide to your total number of man days.
If your two methods give numbers that are hugely different, maybe you need to think about it a bit more. However, if they are in the same ballpark, then you may just have a number you can use. In that case, you just need to tart your working up into something you can present to the people you have to get the money from, put on your best smile and go for it!