It is stipulated that Santa Claus exists.

Further, that he spends the night of December 24th circling the globe in a sleigh pulled by flying reindeer. That he gains access to the homes of children that celebrate Christmas children, and that he gives them presents. And that he does this in the dark, unseen.

Granted, it seems... impractical. Over the course of one night, St. Nick has to stop by the home of every Christian child in the world. Of which there are a lot - an indeterminately large number of kids waiting for their gifts.

I decided to figure out how many, how big a task Mr. Claus faces as he races west across the face of the globe, staying ahead of the sun. And I did. Or, anyway, I came up with a pretty solid estimate.

The Methodology

What I wanted to figure out is this: how many Christian children live in each general area of the world. The region is important: where the kids live impacts the feasibility of the thing. If kids are distributed evenly, Santa has all night to reach everyone; if they live in the same place, he has about half as long.

It's impossible to find this information without considering countries; no one tracks demographics based on longitude. So, for every country in the world - of which there are a lot - I really needed to figure out the population broken down by age, religion and time zone.

Thanks to the CIA, we can readily determine populations by age and religion, and, by combining the two measures, roughly approximate the number of Christians for any given age group. (For the purposes of our experiment, people 14-and-under receive presents from Santa.) Time zones are equally easy, via Wikipedia.

The equation is this: compare population of young people with density of Christianity and plot it on the globe. From that, you've got total population and the times at which Santa should hit them. I ignored the mechanics of distance between houses - after all, I can't know how many houses have multiple children, what regions are more densely packed, etc. The math, it seemed, should be easy.

Should be. Isn't. Before getting bogged down in the incredible nuance of the world's religions and time zones that went into determining these numbers, I'll share the end result.

The Result

There are just over 526,000,000 Christian kids under the age of 14 in the world who celebrate Christmas on December 25th. In other words, Santa has to deliver presents to almost 22 million kids an hour, every hour, on the night before Christmas. That's about 365,000 kids a minute; about 6,100 a second. Totally doable.

Especially when you consider the uneven distribution of kids in the world. Santa needs to hit 22 million kids every hour. If Santa starts at the International Date Line and heads west, the first four time zones he passes barely contain that many kids waiting for presents. He's already got three hours in the bank. Until, you know, he gets to Europe, which kind of breaks his schedule.

Here's what Santa's night looks like. Read it from right to left; i.e., east to west.

The Caveats

As I said, the math was harder than it seemed. For your edification, here are the complexities and oddities I encountered - and which indicate you might want to take my calculations with a grain of salt.

• Countries often have multiple time zones. And it isn't always easy to figure out in which the people actually live. France, given its many remote protectorates, has citizens in twelve time zones. Where should I allocate its 12 million kids?
That's one's actually easy, since most live in France which has one time zone. What about the United States? Between the states and our territories, we have eleven time zones, with most of the children in the four time zones that make up the continental US. How do I distribute our 62 million kids? Or Canada's? My point is: there's a lot of guessing and a little relying on Yahoo Answers.
• Not all countries celebrate Christmas on December 25. Santa must love January 5th. That's the day he has most of the night to hit parts of Russia, Georgia and the Ukraine before Eastern Orthodox celebrations on Twelfth Night. This calendar shift takes about 11.5 million kids out of the line-up on the 24th, meaning that on the 5th he can do a leisurely 800,000 kids an hour.
• It can be tricky to determine how many Christians live in a country. Religion doesn't fall within clean lines. Christianity is fluid: some people believe some components, others mix in regional practices. In Zimbabwe, per the CIA, half of the people are syncretic, blending Christianity with native religions. Do they celebrate Christmas? Does Santa stop by? (For my purposes: yes.)
• Not all Christians celebrate Christmas. Until you look at a country-by-country list, you might not realize how many Jehovah's Witnesses there are - particularly in the Caribbean and Latin America - who do not celebrate the holiday. There are also a number of countries with sizable Seventh Day Adventist populations, like the Pitcairn Islands. There is some debate over whether or not Adventists celebrate the holiday; ultimately, they were included.
• Not all children that celebrate Christmas are Christian. The secular elements of Christmas are appealing: a tree in the house? Gifts? Candy? We have to assume that Santa swings by those houses, too, of course. It's impossible to tell who celebrates secular Christmas, so, for the most part, they were left out of the formula. (But in a nod to realism, 5% was added to the total of practicing Americans.)
• The CIA's data isn't always up-to-date. Please see the entry for Cuba, which presents a breakdown of religion with the helpful caveat that the data pre-dates Castro.
• People in the Netherlands and Belgium celebrate Sinterklaas on December 5. Which is basically a festival of Saint Nicholas. (Note: please do not confuse him with Krampus.) However, Christians in those countries still celebrate Christmas, so Santa still brings them presents. They were included.
• Significant digits are cumbersome. And therefore, they were ignored.
• Santa would have more than 24 hours. On Christmas Day, New York City will see just over nine hours of daylight - meaning nearly fifteen hours of dark. In the Northern Hemisphere, Santa has a little more night to play with. If the children were evenly distributed throughout the world, north and south of the equator, the night would average out to twelve hours. But, like the rest of the population, more children live north of the equator, meaning that on average, the nights are longer - meaning Santa has more than twenty-four hours. Even if we gave him 26 hours, he'd still need to cover 21 million kids an hour. So let's just say twenty-four and move on.

Below, a time zone-by-time zone breakdown of Santa's trip west, delineating how many children Santa has to serve in each and how that compares to the total number of children in the region and the children awaiting presents in the world as a whole.

Over half a billion kids in the span of one night, all while distracting the experts at NORAD with gallivanting decoys. If anyone has ever deserved sainthood, it's Nick.