Estimating a project – How long is a piece of string!

stringAs part of my new role and throughout my time as a Project manager I’ve been tasked with estimating projects, many times with very little information to go on. My response when I had no or little information was

“How long is a piece of sting?”

But That answer is as useful as a chocolate fireguard, so what do you do?!

I’d like to first explain the information that you truly need in order to estimate a project properly.  Now I’m taking a perfect world view here and the idealist view that all of the information is just waiting for you.



  • First, you need a client brief or challenge, and not just one that your consultant has written on the back of a fag packet, but one that the client has agreed that is what they want or need a solution for.
  • Next, you need to know the clients budget. Before you click off this blog thinking “OMG that’s the point of estimating” I need to point out that this doesn’t have to be a figure from the client, it could be from the client, it could be a budget that we want to work towards and in a lovely world where everything is perfect we’d have an open budget, a ‘Tell us how much we need to spend to get X” budget.
  • Then, we need to look at the solution or solutions that we are purposing, one solution is perfect but two might be needed to give the client a choice.
  • Once a solution(s) have been chosen we need to look at the tasks and deliverables that will make up the project
  • We need to look at the technical requirements and get these estimated from the developers
  • Now being an ex Project manager, I am of course going to need to look at how much management this client and project will require
  • Now we get into deeper thought areas.  What are the risks of this project, do we need to add time or costs to cover high risks?
  • And one thing that I find people forget to include in their estimates is “Do we have the resources in house to deliver this?”  If you don’t you need to think about the impact either using freelance or a partner will have on time and cost

So that’s the perfect world and if you have all of that you should be ready to get your excel sheet out along with your Gantt chart and start putting all that into the estimation mix and come out with an estimate for cost and duration.

But what do you do if you don’t have all that? Rarely it’s a perfect world and sometimes we have to use our knowledge in a different way to come out with the estimates.

You will still need to have a client brief / challenge, this is a must. Once you have this and agreed with your internal team as to the solution, you can start to define the ‘length of string’.  We take all of the factors above and we write down the parameters that we use to fill in the blanks

These are the areas that you need to make sure you define

  • Tasks
  • Deliverables
  • Functional requirements
  • Management
  • Risks
  • Resources

You can define what tasks you’ll perform,  what you’ll deliver and how many amends to those deliverables, look at a typical project and create a requirements list and the level of effort to deliver this, next you can write down what percentage of the project (or the hours) that you’ll need for management.  You should definitely write all the risks down and turn them into assumptions. Resources is a little harder but if you don’t have a team looking after you workload then a quick five minute chat with other project managers should  give the information as to how much work is coming in and how you might service this project.

The key to creating an estimate when you don’t have all of the information is to define and document all of the assumptions you’ve made, make these clear in your proposal back to the client and for your sanity, the clients happiness and not turning your hair grey, don’t hide crucial information in small print at the back of the proposal.

So from now on let’s ditch the line

“How long is a piece of string?!”

and replace it with,

“I think the string is this length and if it is that long I estimate it’ll cost…”