The question "How do Muggle-borns end up with magical ability?" got me to wondering how many wizards and witches there were on the planet during the events of the Harry Potter series.

Was there any information given regarding this, either in the books or from JK Rowling herself? If there is not, then a best guess calculation would suffice.

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    I have also wondered this. Is there something like 25% more people in the world that the normal "Muggles" don't know about? – Jack B Nimble May 5 '11 at 17:21
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    @Jack: that would just raise further questions...where would the food for this population come from? Where are the wizard's farms? Really, the more you look into the HP world, the more problems you start to see. It falls apart very quickly, until one must assume that the books are fictional (with no internal consistency to support suspension of disbelief) or that 99% of characters have the IQ of a doorknob. – Jeff May 5 '11 at 18:07
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    @Jeff - Judging by the tactics employed by both sides, I'm gonna go with the doorknob theory :) – DVK-on-Ahch-To May 5 '11 at 18:14
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    @Jeff: While it may fall apart, there could be explanations that tie in with magic. To me, it holds together better than Star Wars does with a lot of inconsistances like a desert planet supporting so many large life forms without vegetation to supply the food chain. One of those worlds has a built-in explanation, one doesn't. (And maybe magical farms, within their boundaries, are like the tardis: bigger on the inside.) – Tango Jun 12 '11 at 16:14
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    @Tango - it's from comment #2 by Jeff. "99% of characters have the IQ of a doorknob" – DVK-on-Ahch-To Jun 12 '11 at 17:08
up vote 54 down vote accepted

I'm guessing between 300,000 and 1 million world wide. I'll explain how I got these numbers in the next paragraphs.

We do have a few solid leads, as Ryan has pointed out. I'm going to take the numbers given by Ryan, and a few other things, and try to get some numbers straight.

First of all, the biggest point is the size of the World Cup stadium. 100,000. That means there is at least that many wizards in the world, or at least, human-type creatures in the magical world.

Hogwarts must have between 300-800 students, with a number of teachers as well. But, given that there must be between 40-100 per year, and a life expectancy somewhat higher than a Muggle (Let's say, 80-100 years), I'm guessing the English population to be around 3000-10,000. This seems to be fairly consistent with the number of shops in Diagon Alley, the number of people working for the ministry of magic, etc.

Further proof of this number can be found in the Goblet of Fire. It's mentioned there that there is 200 portkeys put around England for people to travel to the World Cup. The one that we see there had a total of 11 people gathered around it. Assuming that the average is about 10 per portkey, that gives 2000 people going to the world cup. That number seems consistent with the number of wizards in England at around 4K-10K, given that at most half of the population wanted to go to the cup.

In the year 2001, there were about 60 million people, according to UK census statistics. Given the assumption that the population is roughly equivalent in every country, and a world population of about 6 billion in that year, there is about 100 times more wizards in the world than there is in England. That brings the estimate to between 300,000 and 1 million wizards in the entire world.

This number is consistent with the world cup. Given that transportation isn't much of an issue, but there is no television, it's reasonable to assume that between one tenth and one third of the world population of wizards could in fact attend the world cup.

  • @muntoo: Good luck! – PearsonArtPhoto May 9 '11 at 1:31
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    AFAICT, Hogwarts seemed to take something like 40 students in a year, which suggests something around your lower estimates. – David Thornley May 10 '11 at 2:23
  • @DavidThornley: That's try, hence the 300 number for the number of students. But some reports vary. – PearsonArtPhoto May 10 '11 at 3:04
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    Wow, well researched! :) – Dharini Chandrasekaran Jul 12 '11 at 17:52
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    Using these numbers, the Weasley family is between 0.26% and 0.08% of the wizarding population of England. – cbirdsong Oct 23 '15 at 18:11

Here's a bit from the Harry Potter Wiki:

There is some confusion regarding the population of the wizarding world. The year Harry Potter entered Hogwarts School of Witchcraft and Wizardry, there were forty students that started school. This seems to indicate a very low birth rate, or a very low number of witches and wizards in Great Britain and Ireland, or a combination of both. Also, J. K. Rowling has stated that she imagines the wizarding population of the U.K. to be around 3,000. This estimate, although seemingly small, is understandable; a larger population would be far harder to hide from Muggles. However, she also stated that the number of students attending Hogwarts was around 1,000, which seems inconsistent with the population estimate. Harry once observed in one Quidditch match that three-quarters of the stadium was supporting Gryffindor, while the Slytherin supporters numbered around 200. There are a large number of government departments, and Harry Potter observes hundreds of witches and wizards in the Ministry of Magic's Atrium alone. This would appear to be too large for such a small population. The Quidditch World Cup stadium could hold 100,000 and was built by a Ministry task force of five hundred. It seems very unlikely that a sixth of the entire country worked for a full year on one single project. Though it is possible that the Ministry could have hired out from other countries.

It sounds like there may be some conflicting numbers, or rather, numbers that don't seem to make sense.

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    Rowling has stated previously that she isn't very good at keeping the numbers straight. – Jack B Nimble May 5 '11 at 17:33
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    Clearly the Weasleys don't have low birthrate problems. And the books follow the modern modern socio-economic birthrate preference where the richer people have fewer children (such as the Malfoys). – Jack B Nimble May 5 '11 at 17:36
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    I think that, since Harry was born around the height of "the troubles with Voldermort", it is understandable that his year, a few before it, and maybe one after it at Hogwarts would have a smaller number of students. We would expect a large rise in the number of births shortly after Voldermort went AWOL. – TZHX May 6 '11 at 9:17
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    @Ryan - I disagree. The # of fighters was significantly lower (including as a percentage of population). Wasn't there like a trotalm of couple dozen people in both Death Eaters and OOP? – DVK-on-Ahch-To May 9 '11 at 18:18
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    Yes, but the historical baby boom didn't only involve people who fought in the war, it was a general increase in birth rates over the entire population. I is attributed to increased optimism of the population as a whole (unemployment declines and easier access to education are other reasons). I would think that all of the fear that Voldemort created during his first rise would stifle birth rates as people were terrified to even leave their homes. Once that terror had ended, it is safe to assume they would make up for lost time. – Ryan May 9 '11 at 20:09

Approximately no more than 221,300. Math:

  • Harry has 4 roommates at Hogwarts. It is referred to as the "1st year Boy's Dorm" etc singular.
  • There are probably an equal number of witches in the girl's dorm. This makes 10 Gryffindors per year
  • There are 4 houses. This makes 40 wizards per year.
  • There are 7 years, making there 240 children in Hogwarts.
  • Hogwarts is probably the only school in the UK, considering that it also seems to draw students from Ireland etc. There may actually be far rarer than one per country when you look at how the triwizard cup works. We will say it is 1 per UK, and that other areas have similar densities of wizards.
  • Since Harry's parents died in 1981 and he was 1, he was born in 1980. If he attended school in the fall after his 11th birthday, he would begin school in 1991.
  • According to the 2011 survey a bit over 10% of people were between the ages of 10-19. Let's say it is only 10% because 19 year old wizards do other things and wizards live longer. This is the least sound statistic in this math as the survey is 20 years later and we have no way to know if wizard's age demographics match muggle demographics.
  • That makes 2,400 wizards in the UK
  • The population of the UK was 57.45M in 1990
  • 2400 / 57.45M = 0.00004192139 wizard per human in England
  • The world population is in 1990 was 5.279B
  • 7.046B * 0.00003795666 = 221,303 wizards
  • Rounded to 4 significant figures is 221,300 wizards
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    Very interesting thoughts, Thanks! I would only like to add that, at a count of 40 wizards per year and there are seven school years to be taken into consideration, this would amount to 280 children, not 240, and consequently the population of wizard in the UK would amount to about 2800.. – user28645 Jun 24 '14 at 16:08
  • I think the calculation is an underestimate, because a Wizard life expectation is higher than Muggle, due to a better medical care. Wizards can achieve age of 100+ years without getting senile and fragile. – TimSparrow Jan 9 at 15:54
  • You're missing one other important point: during a significant conflict (such as the 70s wizarding war), birth numbers are depressed. Following such a conflict, there is a baby boom. If Harry's year was, for example, 80% of the 'normal' size, it would change your numbers significantly. – Jeff Jan 10 at 14:38
  • This is a good answer, but you forgot that many wizards seek immortality, and often they live a lot longer than the Muggle life expectancy. Dumbledore was 150 at the time of the books, and he was still fit to be a teacher. He never meddled with the Dark Arts and didn't successfully extend his life. The oldest person ever was 755 when he died, so people who artificially extend their life through Dark Arts or otherwise can live for a very long time. The elderly population is a lot bigger than Muggles – lightofdeanthomas Feb 3 at 0:51
  • you forgot about homeschooled wizards – Jungkook Feb 28 at 14:57

There are less seven thousand wizards in England during the twentieth century. About three thousand during the events of the series.

Less than one out of every thousand wizards is an animagus

It is immensely difficult to change oneself into an Animagus and the process, which is complex and time-consuming, can go dramatically wrong. As a result, it is believed that fewer than one in a thousand witches or wizards are Animagi.
Pottermore - Animagi (behind paywall)

and there are less than seven Animagi in the twentieth century

“Because . . . because people would know if Peter Pettigrew had been an Animagus. We did Animagi in class with Professor McGonagall. And I looked them up when I did my homework — the Ministry of Magic keeps tabs on witches and wizards who can become animals; there’s a register showing what animal they become, and their markings and things . . . and I went and looked Professor McGonagall up on the register, and there have been only seven Animagi this century, and Pettigrew’s name wasn’t on the list —”

Harry Potter and the Prisoner of Azkaban - Chapter 18

(Yes, there were a few unregistered ones, but both of these statistics are referring to known animagi.)

This puts a maximum bound at seven thousand wizards in England during the twentieth century.

The number of wizards alive during the seven years in which the books are set would be considerably lower, consistent with Rowling's estimate of 3,000.

Let's say three thousand [wizards living in Britain], actually, thinking about it, and then think of all the magical creatures, some of which appear human. So then you've got things like hags, trolls, ogres and so on, so that's really bumping up your numbers. And then you've got the world of sad people like Filch and Figg who are kind of part of the world but are hangers on. That's going to bump you up a bit as well, so it's a more sizable, total magical community that needs hiding, concealing, but don't hold me to these figures, because that's not how I think.

Anelli, Melissa and Emerson Spartz. "The Leaky Cauldron and MuggleNet interview Joanne Kathleen Rowling: Part Two," The Leaky Cauldron, 16 July 2005

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    There are seven registered animagi and at least four unregistered simply within the main cast of the novels. It's possible that they represent less than a few percent of all animagi. Note that you're conflating a pottermore "omniscient narrator" article with an in-universe figure given by Hermione. – Valorum Sep 7 '17 at 22:56
  • @Valorum - Hermione was quoting a figure she read. The Pottermore article in question was written in the style of an in-universe document, not the usual omniscient narrator. (It addresses the reader as if they themselves were a wizard.) Thus, I'm assuming that, like Hermione, it wasn't including any of the unknown animagi in its count. – ibid Sep 7 '17 at 23:07
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    This is based on a misunderstanding in statistics. As a rule, general stats about likelihood cannot be extrapulated to population. For example, if there's a one-in-a-million chance to win the lottery, ten lottery winners do not show the population as 10 million. – TheAsh Sep 11 '17 at 11:08
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    @TheAsh - Though this a work of fiction, and decisions of Rowling generally are based on misunderstandings of statistics. – ibid Sep 11 '17 at 11:13
  • Actually, she clearly says that she doesnt think that way. >"That's going to bump you up a bit as well, so it's a more sizable, total magical community that needs hiding, concealing, but don't hold me to these figures, because that's not how I think." – TheAsh Sep 11 '17 at 11:30

Although not an original content of J.K. herself, an article about Barry Winkle in The Daily Prophet, 14 August, 1991, gives us a lower bound:

Barry Wee Willie Winkle celebrates his 755th birthday in style tonight by throwing a huge party for all the wizards and witches he has ever known. 30 million are expected to attend tonight.

By looking at any population growth graph through centuries we can estimate that majority of those 30 million people are still alive. This would also imply that roughly more than 0.3 % of people are wizards.

  • Sounds like an easter egg :) I like it! – Gallifreyan Mar 23 '17 at 17:57

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