It's pretty difficult to estimate, 'coz it depends when where all you wish to travel and for how long! But let's assume that you have about a year's time to explore, then you'd approximately need 60K-70K per month (including transport, stay, food and activities) - so in total it'll be approximately 8 to 10 Lakhs!
You need to first map out the route and where n all you want to stop in your Worls tour. Then you have to find the cost for travel, stay, food and sightseeing