I actually have no clue how much money it will take. I can walk you through the process I used, but you probably won't be satisfied with the result....

First, a lot of my decisions are based on my own experience from past travels. I know I have a tendency to camp. I know I almost never cook my own food, but always find the cheapest restaurants (preferably ones that I can get 2 means for the price of 1). I know I will drink alcohol periodically.

I've also looked into estimates of what it takes to travel in various parts of the world and separated the world into 4 "tiers" of countries, based on cost estimates by others and modified by my own travel style. For typical daily expenses (NOT visas, insurance, cell phone SIM cards, shipping, maintenance, etc. etc.) I came up with the following list. I have no clue how accurate it will be outside the USA.

Tier 1: $60 - $100 / day
The expensive parts of Europe

Tier 2: $40 - $80 / day
USA, Canada, Europe (less expensive), Northern Asia (Russia, etc.), Australia

Tier 3: $30 - $50 / day
Central America, South America

Tier 4: $20 - $50 / day
Africa, Southern Asia

I then planned out generically how much time I want to spend in various parts of the world to get a first cut at how much money I might need for the trip. Then I started planning some possible routes to find out more realistically how much time I will spend in each location. Then I start connecting those routes to the above numbers. Then I add in funding for things like shipping between continents, maintenance, visas, touristy things, the carnet, etc.

In the end I come up with a list of numbers that give me a goal to reach before I leave. It is incredibly generic, but it gives me something to shoot for. Here are some of the ranges of funds I come up with using the above, varying route and daily expenses:

2 years: $29k - $80k
3 years: $48k - $105k
4 years: $80k - $160k

Not very helpful is it?

My actual funds also took a severe hit recently: Selling my house was a lot more expensive than I expected because of the bad housing market.

How long will my money last? No clue. I am 100% confident of 2 years. I am 70% confident of 3 years. I think there is a reasonable chance of 4 years if I am careful, or my numbers are overly pessimistic.

But all of that could change. I might decide to skip Australia to spend more time in Europe. I might look for work while on the road. I might have been pessimistic in my cost estimates. I might even delay leaving so that I can work up more money.

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Traveling The World Since: 2011
Blog: The Seductive Life (General Travel)