Ok. After reading your question, I can easily judge that you haven’t even started researching on the world tour yet. So, I will quickly assume that you are planning to visit all the major destinations – worth-see places across all continents including Antarctica and want to experience all the popular must-do the world has on offer.
Africa: 2 months.
Europe (Including UK): 3 months
Scan & Russia (Including Iceland and the Far North): 2 months
The Middle East & Central Asia: 2 months
India, Nepal & China: 2 months
Japan: 1 month
South-east Asia: 2 months
Australia & New Zealand: 1 month
Antarctica: 1 month
South America: 2 months
North America & Canada: 2 months
The above time includes interstate & international travel and sightseeing. It also includes regular breaks you may need to rest your sore feet and just relax once in a while.
But it excludes the time you will be spending while volunteering in India and living with monks, trekking to Everest Base Camp in Nepal, learning MMA in Thailand, taking an advanced scuba diving course in Spain, etc. etc. Let’s assume such long breaks will add up another 12-14 months in your itinerary.
You have to also assume that there can be some emergency halts due to issues related to visas, border crossings, political conditions, personal health, etc. When you travel for a long, you are bound to the fell sick. Let’s keep another 2 months for such contingencies.
Okay, time to add up the “time”. Total is around 3 years.
There is no direct, plain, and simple formula to calculate the total cost of your super long trip. Some places will be shit expensive and others will be dirt cheap. So, we shall take an average here. Europe, Scan, Russia, Australia, and the US are expensive($100 per day per person). South America, Central Asia, Middle East, Africa, India, South East Asia are cheap ($50 per day per person – lavishly). The total comes to around – $83k for three years.
Let’s add up major airfares, visa fees, etc. – another $25k.
And, popular activities – sky diving, trekking, martial arts course, motorcycle tours, luxury train travels, posh cruises, exclusive beach parties, etc., etc. How can you miss such fun? Add another $25k.
Total : US $ 133k.
We are short of $17k to the magic figure of $150k. So let’s push this missing $17k for all that is left. You will also need good travel + health insurance and some emergency cash in an emergency credit card (should be enough to fund you a week of food n stay plus return ticket back home from the farthest corner of the world), plus the same amount to be kept with a family member who can wire you this money in case you are robbed off everything. You will also need some money to buy stuff (backpack, gadgets, etc) before you set off and you will need to buy some stuff (lost, robbed, broken, gifted away!!) during the course of this long journey.
Let me summarize this:
You will need US $150k and 3 years to tour the world solo, backpacker’s style.
Disclaimer: I have calculated this rough amount based upon my style of traveling, interests, eating, and sleeping habits. This may vary with other individuals.