On average how long does it take you to design a web site in hours?
Do you mean designing it in a graphics program or the actual HTML/CSS/Javascript too? Does this include adding pages/content? How many pages are we talking about?
64.5 hours and 8min.
This is such a vague question and impossible to answer.
What kind of site are we talking?
Is the website’s topic something you know about or do you have to do research on it?
Does the content need to be written or is the content already available and just needs to be optimised?
What features?
Branding?
Identity?
Will there be dynamic content?
Will there be a blog?
Will there be eCommerce functionality?
Will there be user management?
Multiple authors?
Multi-lingual site?
Budget?
Custom icons?
Custom illustrations?
AJAX?
CMS? If yes, custom or off-the-shelf?
Do you know how to work with that specific CMS or do you have to learn it first?
SEO?
SEM?
Multimedia content such as video?
What about skill set?
Are you a fast worker? Slow worker?
… and so on and so forth.
It just isn’t possible to give a sensible answer to your question and any attempt at doing so without knowing the specifics seems utterly absurd to me.
:agree:
We had this question about a month ago… same wording too if I’m not mistaken.
Oh well, I guess people still think people can pull numbers out of the air 
i think the answer to the question is however long it takes YOU to design whatever YOU consider to be a WEB SITE.
otherwise…the question has way too many variables to answer. [as has been pointed out already]
your question indicates your lack of experience [not being critical]…
but my point is that i suggest you design a few sites and you will know your answer…in the meantime…get any work you can…for any price…and put in whatever hours are necessary to get the job done. [being content that you have been given the opportunity to design a web site!]
He asked about DESIGN not bulding it.
I guess the time needed to design a layout (not the screens, templates) is pretty much the same.
Seriously, and no disrespect towards anyone intended, it’s like asking, “How high is up?” I am a somewhat-proficient amateur (one of Alex’s “master of none” designers ), and I can find a pre-designed template on the Interwebz, slam in some content, and have a “web site” up by dinnertime. But that’s barely designing anything. I can design a new site from the ground up and have an index page, a content template page, and the usual “About,” “Links,” and so forth pages done, with background graphics, navigation, simple JS functions, and the like, in a weekend. But that’s just me, with my limited skill set and knowledge. Your mileage, like everyone else’s, may vary.
For further reference, see Kohoutek’s reply.