At the beginning of almost every project (and even sometimes midway through them) we are asked to create a requirements plan and estimate the time required on tasks and the number of BAs necessary to execute it. In a later post I’ll talk about the actual plan items, but we do have a rule of thumb for how many BAs you need on a project.
We have a standard metric we use: we suggest 1 BA can support 4 to 8 developers. Typically I suggest 1 BA to support 4 to 6 developers though, as 8 is a stretch on many projects. Of course this number is highly dependent on the context of your project, so treat it as a rule of thumb only.
As an example, right now we have 7 developers working on rebuilding existing functionality from an existing site and it’s required just over 1 BA to work on the requirements for it. And even at that, the BA is pretty stretched to get them done as fast as the dev team needs them. And in another part of the project, we have 1.5 BAs supporting about 4 developers who are doing defect testing – but they are also very intensely focused on UAT activities.