There is no good revenge calculator to use as a baseline because it makes a broad assumption about demand for your audience.
if you care only about ad revenue, look for subjects that have high cpcs in Adsense. Those are a good place to start as the potential profit is more easily modelable. However, you also at wind up with subjects that are very esoteric or otherwise boring to you.
The other options is something you like as a subject to build content or a community around. You may have lower revenue but a much more fulfilling project.
My one major piece of advice is to look at how you creat unique value overall. If your site is easily replaced then the valeu is low and your staying power in the face of competition is very low.
If your site is something that users can't live without, then you are far better off.
I currently pull in about $300k/year in revenue and $80-$100k/year in profit.
I use a number of credits cards for the ads to get points, so I consider it a source of revenue and vacations.
It's not easy to make a site like this and it as been a long road, but a worthwhile one.
(Posting anon as I prefer not to disclose revenues publicly)