I am experienced tester. Mostly I estimate any project testing time based on requirements. But Now I have interesting question that for ex : I have checked requirement and if developer is saying that they will need 30 days to complete development.

so at this stage how should I estimate testing time? based on given requirements or based on estimated development time?

I am thinking that if developer need 30 days to develop then as a tester I need at least 1/4 time means 7-8 days to complete testing , Is this right way to estimate testing time?


This depends on many factors. How accurate and reliable are developer estimates? For throughout the testing needs to be? How efficient you are in testing compared to the developer? How you count time needed for bug fixing and re-testing (and re-fixing and re-re-testing); is it development or testing time?

Old rule of thumb is to take original development estimate and multiply it by π, and use that as the total time used for the feature. ;-)


As an initial guesstimate I would equal the developers estimation.

Obviously you should adjust it to your circumstances, for example do you need to develop automation ? if yes do you have an infrastructure you are familiar with ? is this a new project ? how complex is it compared to previous project you tested ? are there special risk regarding quality like inexperienced developers, unclear requirements, immature technology or lack of test equipment. and so on...


As it has been said already, it depends but, going by development time does not tell you that much. Some guys can code a mile a minute while others are snails. Some do good unit testing while others don't do any.

My process is as follows:

1) Requirements documents. If available, I always estimate based on the requirements document. I outline my testing and estimate the areas to be tested, the number of cases and so on from this document.


2) I take in consideration past experience with the developer(s). How buggy their code has been. What has been their fix turnaround time.

3) Size of the development team vs my team.

4) Whether all code is in-house or are outside libraries used (new to us libraries).

5) How critical is this development. It is brand new product or an add on feature (most likely your case). How many and what other systems does it touch? Basicaly, do we have to regress of bunch of other stuff as well.

In either case, my estimate normally starts after the code has been tested/soaked for a week or so. Many times we find critical bugs the first week, fixes for which eat into testing time. In my group, my testing time does not start until we accept the code drop, which we will do after running a series of tests, i.e. soak time.

Hope this helps.

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