If you're going from the USA, you would find the info on that at the website of our local 1w member, www.aa.com

Strangely enough, there are two completely different kinds of RTW. Paid RTW's use the oneworld Explorer basis, in which your fare is a function of the number of continents you hit (and of your class of service, natch). If you get one as an award, it's still on the 1w carriers, but the number of miles required depends not on continents but on total distance flown.