This seems to be a very common question faced by many test managers. “What do you think should be the ratio of testers to developers?”. But, there is no correct answer to this question. Rather, it depends on various factors including the job profile of testers in the project, the complexity and size of the project.
Since I was the first tester in my current company, it was part of my job to decide how many more (a minimum number of) testers were required for proper testing of our products. The minimum ratio I came up with was a 1 tester for 3 developers ratio. I thought the ratio would be optimal for our company – meaning some over-time, but not so much for our testers. Also, the ratio was decided by considering we will spend very less time on documentation, and will concentrate mostly on bug hunting and quality determination.
Then, I came across this document today which I found very informative. It states that optimal ratios may vary according to the projects and tasks required to be taken care of by the testers.
And, also that one should give proper thought to the ratio decision and resource allocation for good results.