End the mystery. (Photo: World Taxi Meter)

How much should a cab ride cost you? The answer naturally varies but it's a frustrating question, in part due to how much the fare can vary depending on the taxi, the driver, the route, the traffic, and the time of day. All these factors can cause the fare to shift a few bucks one way or another.

Most frustrating to the average person, however, is that no one knows what the range should even be. What's the ballpark for a cab fare? In Baltimore on New Year's Eve a few months ago, I and a few others rode a cab home and upon arrival, had to pay a surprisingly high amount of money that didn't fit with what the cab driver told us. Taxi riders should generally know what to expect, what questions to ask, and how to diplomatically discuss and negotiate to at least understand if the fare seems inappropriate.

D.C. residents, the perfect taxi tool is officially here — behold, the World Taxi Meter, an international taxi-fare calculator. It's now online in its beta version as well as available in mobile form for the confused walkers in need of a ride.

Choose your city, your location and your destination, and your time of day, and boom, there's your taxi fare down to the cent.

If you're considering early afternoon today, for instance, I've calculated that a cab ride from the Watergate to Dupont Circle would, presumably, cost a person $7.94. Try that same trip at 9 p.m. tonight, however, and it's a few cents more expensive at $8.09. Or say I wanted to go now to the White House: $6.89. Or to Bethesda: $19.43. The calculation includes a 15% tip.

Underneath the calculations and Google-mapped cab route are city-specific bits of information about the area's relevant cab companies and some pointers for the area, such as how a declared snow emergency will affect the fare. I'm impressed and surprised at how slick this all seems, especially since the World Taxi Meter's founders all live in Europe. The idea seems to have developed in Madrid, where two of three men currently live, and to have been around for the past couple years. The site has received more than 475,000 searches in a month and works in 39 cities around the world (including D.C.), according to the site.

The fare numbers shouldn't be treated as gospel, but I love the tool's versatility for determining what a taxi trip should roughly cost. The application would be quite useful when traveling, I imagine, and to get a general sense of what a cab ride should cost. World Taxi Meter's people make pains to emphasize that these are estimates on the site and rid themselves of any liability — my guess is that they've encountered a couple people angry to find that the estimates didn't at all match the reality. Try it out the next time you need to ride a taxi anywhere in D.C. I'm definitely not a regular rider myself, and I'm curious to know how the calculated fare matches up to the real thing.