In The World’s Cheapest Destinations book I break down a lot of typical expenses in different countries for recurring items like lodging, food, drinks, and ground transportation. I then provide some rather wide ranges of what it’ll probably cost you on a day-to-day basis for budget and mid-range travelers.

The problem is, I don’t know your money habits or how you travel, so the biggest variable of all is always going to be missing: you. I don’t know how much you need to buy beforehand, how many sacrifices you’ll willing to make to save money on lodging or buses, or how much you like to shop. I also don’t know how much you are going to party. Or whether friends are going to meet up with you along the way somewhere. Or whether you are willing to splurge on worthy adventure excursions or side tours. Obviously your choice of destinations makes a massive difference—three months in Central America will cost a fraction of three months in Scandinavia no matter how you travel—but budgets vary a lot from person to person.

Now that half the travelers on RTW trips seem to be bloggers as well, you can get a peek into the process of how much people are actually spending during their round-the-world trip—and what has driven up expenses beyond what they expected. Follow your favorites for a while and you’ll get an idea of what they’re spending. Here are some good posts and tools with real numbers though to get you started.

In Living the Dream, this guy spent far more than he had expected, even though he was in Southeast Asia: more than $16K over 152 days. He breaks down the reasons in the link above.

I like perpetual traveler Nora Dunn a lot and she even did a 5 Things I Always Pack guest post for me at Practical Travel Gear, so I’ll trust her incredibly detailed advice on traveling the world for a year for $14,000.

I wrote this article close to five years ago for Transitions Abroad, but it still holds true: fly to the cheap country clusters and save.

This Budget Your Trip Widget looks promising, though I have never given it more than a cursory test. Plus my Cusco is not your Cusco—once again—but it should help you get a rough idea. Plus you can track expenses through there if you’re so inclined. Here’s the associated blog, with more advice.

For years and years of budget breakdowns for shoestring traveler Andy Graham, check out the HoboTraveler site. He’s at the ascetic end of the scale, typically getting by on less than $500 per month, so it’ll show you what’s possible if you can cut a lot of things out of your life.

There is also a lot of good specific advice on message boards from the likes of Lonely Planet and BootsnAll. But do your homework before you post a question on there: people don’t take kindly to lazy people just looking for quick (and probably wrong) guestimates.

Flickr photo (a hostel room in Paris) by Fierce Powahs.