Quote Originally Posted by Midgardsormr View Post
Medieval Demographics Made Easy

Be sure to check out the Calculators and Spreadsheets bit at the very bottom of the page.
That's a very useful site. Sets good baselines to use anyways. One problem with fantasy is of course it could completely screw everything up. Lets say there is common magic that doubles the crop yield per acre or some such. That sort of thing plus constant monsters in an area is bound to cause changes to the demographics in pretty unpredictable ways.