If you’ve ever watched Buffy the Vampire Slayer, you’ve always had one question. How many vampires are there, anyway? Fortunately, that’s sort of answerable.
First thing: Assume the vampire population is more or less constant. Maybe Buffy’s driving them extinct. But I think the evidence supports the assumption that it is actually constant. From the subjunctive episode (you know the one), we know that if Buffy Summers had never come to Sunnydale then that town would be apocalyptically unpleasant and there would be more vampires and demons worldwide. In other words, she’s in the best possible place and routinely saving the world and barely maintaining the status quo. Most likely, every other Slayer before her did the same.
Google tells me that apparently the equilibrium numbers in a closed system are eighteen vampires and the population of Sunnydale. But keep in mind that it’s not a closed system. Vampires and other nasties are continually arriving there for plot reasons that were actually justified, and they’re also being killed off because it’s a TV show and the good guys have a tendency to win.
To find the vampire population, the first step is find how fast they’re dying off. Since the show only follows the protagonists and doesn’t show continually updated demographic information, the best we can do is find a lower bound on this.
In the name of research (and for no other reason; it definitely wasn’t just an excuse), I watched about half the episodes. About 1.7 vampires get turned to dust per episode, but that doesn’t help much because we need number of vampires per unit time. The better method is to look at how many vampires Buffy stakes per hunt. It’s tricky because it only shows a nonrepresentative sample of the slayings. Most of the routine vampire-slaying takes place off screen along with the routine-vampire slaying.
We can pick up some clues from season 2 episode 11 (“Ted”). Buffy says that she killed three vampires, and implies that that’s an unusually high number for a single night’s hunting. A few days later, Buffy is out of commission so Giles has to go patrol instead. That’s important because it means that missing a single day is a problem. So based on that episode, somewhere between zero and three vampires die in Sunnydale every day or two.
(OK, “die” is probably the wrong word under the circumstances. Whatever.)
Assume there are 365 days in a year and Buffy goes on patrol one out of every three days. (It has to be frequent enough that her missing a day means that someone else has to do it, but infrequent enough that she can still do normal highschooler things occasionally when the plot demands it.) Rounding the average down to one vampire per patrol, that means that a minimum of 122 vampires die per year. Actually more, because remember this is only in Sunnydale. Presumably vampires do die outside there; maybe they can slip on a banana peel or something.
So to find the number of vampires at any given time, we’d just need the average age of a vampire. If the life expectancy at conversion is, say, ten, then there must be a vampire population of 1220 in an average year. Of course, vampires are known for living much longer than that.
The Master is supposed to be one of the oldest known vampires, and is old enough that his appearance changed into something unusually ugly even for a vampire. He’s hundreds or thousands of years old, and nobody knows how many of either. He’s just one data point and probably won’t affect the average much, but the fact that vampire appearance changes with time might be useful. According to Spike (age: ~150), vampires often claim to have been present at the Crucifixion. They’re usually lying, of course, but that at least means that a not-obviously-ancient vampire could plausibly be two millennia old. They’re probably not in the habit of telling lies that can be seen through at a glance.
So 2000 is old but plausible, and the youngest is of course “staked while in the process of climbing out of the grave.” Most of the vampires with stated ages are in the 100 to 300 range. Spike is considered young. And Buffy sometimes identifies vampires by fashion: If someone is dressed like they’re from the 1890s, they probably are from the 1890s. If that works reliably, it implies that most vampires have been around a while.
If we take 150 for the life expectancy, then there would be about 18,250 vampires at any given time, at minimum. Remember that this is assuming that no vampires die ever except for those killed by the Slayer.
Does that number make sense? Maybe. It’s never established how often vampires feed, but it would probably be a lot of unexplained disappearances. Say it’s once a month. (Though it’s probably closer to once a day.) Then it’s 219,000 vampire-related deaths per year. Judging by the incident with the Anointed, they sometimes disguise their work as an accident, but they usually don’t bother.
I’m going to look at just the U.S. from here on, because the statistics are easily available. It has about 4.5% of the human population, so if it has the same vampire-to-human ratio as everywhere else then that would be at least 9,800 casualties of the vampires. It also has hundreds of thousands of missing persons. But fortunately, not many of those stay missing: in 2011 out of six or seven hundred thousand people reported missing there were 2,079 who were not found within a year.
So no, the Buffyverse’s numbers do not check out. There’s not even close to enough missing persons to sustain the minimum vampire population. Even if every single missing person and every single victim of an unsolved murder was killed by a vampire, that would total about 8,000, which is less than the vampire population would kill.
And that was with all conservative assumptions. Buffy is not in fact the sole cause of vampire death, so there would be more vampires not counted in these numbers. If vampires have a life expectancy of more than 150 years, then there would be more total vampire-years and more humans murdered. Vampires probably kill more often than once a month. Buffy probably patrols more than once every three nights; this would mean more vampires killed and that would mean more victims from when they were alive. Er, ambulatory. Those would all result in more people disappearing, a statistic that is fortunately not demonstrated in the real world.
So this was a lower bound. For an upper bound, it’s harder to say. There are few enough vampires that one Slayer can make a huge difference (citation: that subjunctive episode) but enough to justify some kind of world-spanning shadowy organization of Watchers devoted to taking notes on them. But the point is that even the lowest number is very definitely ruled out by the lack of people being murdered.
Therefore, I am pleased to announce that you ARE NOT being stalked by vampires in anything like the numbers depicted in Buffy the Vampire Slayer, or at the very least the show exaggerated the danger.