**Rule of thumb***

As a rule of thumb, each activity of WBS should take less than 80 hours"

Is this statement correct ?


what is the context behind this statement? if it is refering to an actual project, then this could never be correct.

 In one of the books it's mentioned  that each work package in the WBS should not have effort of more then 80hrs.



can u give me the name of the book? coz i am wondering from which basis this book has? efforts could be expressed in terms of e.g. staff-hour, staff-day, staff-month, staff-year, so how come it could not be more than 80 hours? i pressume the info you have posted is not complete.

Although, we have to understand that efforts could never be with or critical, as these are only supplementary to the work packages.

Thanks sam for this link. Now i understand the context. As per your link given, the context is not about efforts, as you have written, but about how WBS are to be prepared and decomposed in relation to the 100% scope. As explained, the first few e.g. 3 levels of WBS could represent 100% scope but as it is decomposed to the lowest level of work packages, it has to meet only certain degree of limits so as quantifying and monitoring will be possible. I may consider this as "best practice" probably by some PMP, BUT TAKE NOTE THAT PMBOK4 has never mentioned about this. I agree with PMBOK4, as this could be project-case-to-case basis, and activity-wise, thus cannot be set as a standard.

The rule of 8/80 just simply says - if your lowest level of WBS has still estiamated duration of more than 10 days (80hours), this means, you can still decompose this to a further level. In similar manner, if your work package has estiamted duration of less than 1 day (8 hours) then this is not workable or may not be a real quantifiyable work or activity.

Again, this is not PMBOK4 standard, so dont be bothered of this. Well, in your actual PM practice, this could be some sorts of consideration.

Projmanpro is correct. Please do not go by such number, in fact I would not expect any PMP question asking such direct number in any questions.

However, you might get in a question something like … “A big task of 2000 man hours was being broken down to smaller pieces of 100 hours each, what is this process called?”…something like this in a better English and well explained by good situation. So you have to assume its WBS.

Similar question is also seen for rough order of magnitude (ROM). PMBOK just gives an example to explain you +/-50%, but it DOES NOT say ROM is +/-50%. You have to use your common sense and assume any such rough figure.

Thanks a ton for the clarification...

This statement is partially correct. You should look at this article for further information: