How to Estimate Your Project Schedule

It seems like I spend a lot of time at the dentist. 

I’m always amazed at the time management and skill management a dentist has. My dentist knows precisely how long specific procedures are going to take and completes the work within the time allotted. Rarely do I find myself waiting for a long time in his waiting room. And even more rarely does he go beyond the time that he has booked for me. To me, this means two things: He is good at estimating how long his work is going to take. He gets his work done on time. 

Estimating In Your Project

I wish that we could all be more like my dentist when it comes to estimating the amount of effort our project work will take. Whether you are using an agile, waterfall, or some hybrid methodology, you are required to estimate the effort of your work. Very often, the excuse that I hear is that we can’t give accurate estimates because we don’t know the possible roadblocks that we will face. But the same is true for my dentist. He doesn’t know whether a tooth will break off unexpectedly, or if a filling will turn into a root canal. But he still seems to estimate the right amount of time. 

The Secret To Good Estimation

Here is the secret to good estimation: 

  1. Break down the task into the smallest possible action steps. Once you have a list of action steps, you can honestly assess how long each will take. 
  2. After you assess the length of time the task will take, ask yourself how long this task would take if everything that could go wrong, did go wrong. 
  3. Add 25% of the time to the amount that you get from the previous calculation. 

Why This Works

While it feels like you are padding your schedule, in reality, the following will happen: 

  • If you estimate based on the smallest amount of work, you will always start with an optimistic estimate. This estimate will only happen in the perfect world. 
  • When thinking about the worst-case scenario, you start to have a more realistic estimate. But you still always tend to think about the best-case outcome of the worst-case scenario. 
  • If you add 25% to the worst-case estimate, then you come out with the most realistic schedule estimate. In some cases, you will deliver the task within the most optimistic timeframe, and in some cases, you will be well-beyond the worst-case schedule estimates. Overall the schedule will lean towards the amounts that you have estimated and adjusted for. 

Don’t overestimate how quickly you can get your work done. Be realistic, and deliver on time. People will find you the most reliable when you finish on time.