Question: > 
> Not Counting the OS And the requirements to run the Development software. The storage space required.
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Strictly speaking from work perspective(company setup and not freelancers).A individual developer ( not considering a build system) unless into areas of video,audio processing( huge raw files) 3d/graphics development.
How much storage space would be required.

* Even if we account for the software trials to download or reading material.is it Right or Safe to assume 20GB would most suffice and any thing more would be a waste and or would be improperly utilized?.
* What is the typical hard disk space allotted per developer in an office setup.This may differ per role or specific requirement and on what type of work the company is into. but on an average for a developer/programmer how much space is normally allotted.

Edit: 

**To Clarify Intent** 

These are questions i had faced by business/management people.I only wish to understand more in this regard to give an answer(or better answer)the next time i come across them. I am neither making assumptions or intend to give offense to any one in this regard.It would be helpful if some links to data online were provided in this regard.

Edit 2:

* The issue as i understand was restricting the storage space to only the saving of work files to discourage extraneous usage...
* Not about scrimping/cost saving on hardware.

Answer: 
My main work machine has a 160GB internal drive, a 160GB external drive, and a 250GB external drive. 
All but the 250GB drive are almost full (which is why I added (at my own expense, btw...) the 250GB drive).

We're using VMWare images a lot, and those tend to get rather large.
3 projects, each with a 20GB image plus a backup image, is 120GB. 
That doesn't include the space needed to install Oracle, WebLogic, 5 JBoss instances, IDEs, office software, operating system, etc. etc. which together take up another 100GB or so.

Then there's documents, eBooks, and whatever else you need. For productivity that'll likely include a few GB of music for iTunes (most anyone I know works better to music, and everyone prefers different music). And yes, I therefore do consider iTunes (or another music library/player) a productivity tool.
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> These are questions i had faced by
>  business/management people
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You do realize that modern internal harddisks cost something like ¢3-5/GB? So you're suggesting that ¢60 should be enough for developer. That's ridiculous, a sounds very dilbertian to make management issue out of it.