What is the population of Hogwarts’ School of Witchcraft and Wizardry?
Who would have thought that such a seemingly simple question would be so vexed? It seems like working out the population of Hogwarts would be a simple process. Sadly it isn’t, not least because the population of Wizarding Britain simply doesn’t make sense, as far as I can work out. The fact that JK Rowling’s statements on the subject are horribly inconsistent only exacerbates matters.
Firstly the alternative hypotheses:
- The “small Hogwarts” hypothesis: Harry’s year is normally sized, at ~40 students. The human population of Hogwarts is normally ~300.
- The “medium Hogwarts” hypothesis: Harry’s year is smaller than average, at ~40 students. The human population of Hogwarts is ~600, but normally closer to 700.
- The “big Hogwarts” hypothesis: Harry’s year is significantly larger than 40 students. The human population of Hogwarts is 1,000+.
In interviews, JK Rowling has suggested 600 and 1,000 for approximate sizes of the student population of Hogwarts. She has also estimated Magical Britain’s population at around 3,000 at the time the books took place. Simple arithmetic quickly shows that this, at least, is pure nonsense. If there are 300 students at Hogwarts, then 1/10 of the population is at any one time a student at Hogwarts, suggesting an average magical lifespan of no more than 70, which is just about possible, even with the existence of characters such as two Dumbledores, Griselda Marchbanks and so on clearly well over 100, but fairly unlikely, and clearly makes nonsense of her two in-interview positions on the population of Hogwarts.
JK Rowling’s statements in interviews, and especially those having to do with orders of magnitude, basic arithmetic and so on, are notoriously unreliable, however, and so we must go back to first principles to estimate the size of the student population of Hogwarts. In doing so, we will start from the facts which are indisputably canonical — that is, the information given to us in the seven published novels concerning the life of Harry Potter — and then shall add in evidence from the other “deuterocanonical” (to borrow a term) sources: the three supplementary books by Rowling (Quidditch through the Ages, Fantastic Beasts and Where to Find Them, and Tales of Beedle the Bard), anything else written “in universe” by JK Rowling (for instance, the short story featuring Sirius and James, and set before the events of PS/SS), and Pottermore. Evidence from JK Rowlings own statements in interviews and on any material other than that enumerated above may be discussed but will not be taken as evidence as to the workings of the wizarding world.
Hogwarts in the Books
Most of the evidence from the books points to there being no more than 40 students in Harry’s year:
- There are 29 students mentioned by name in the books who we know are part of Harry’s year. 8 are Gryffindor, 8 Slytherin, 6 Ravenclaw, 4 Hufflepuff, and 3 whose houses are unknown. There is also at least one character (Zacharias Smith) who is likely to be, but is not necessarily, in Harry’s year.
- In PS/SS, there are 20 brooms set out for the Slytherin and Gryffindor students’ flying lesson.[PS109]
- In PS/SS, when the first years are first shown to the Gryffindor common room, Percy shows the boys “their dormitory”, implying that the first years only have one boys’ dorm. The same is true for the girls.[PS96]
- In CoS, there are “about” 20 earmuffs set out for the Gryffindor and Hufflepuff students’ herbology lesson repotting mandrakes.
Unfortunately, an incident in chapter 12 of OotP complicates things:
- In OotP, there are “thirty eagerly listening classmates”[OOTP221] in Harry’s Defence Against the Dark Arts.
There can therefore be no more than “about” 20 Gryffindors and Hufflepuffs together, and no more than 20 Slytherins and Gryffindors together. There are at least 8 Slytherins, 8 Gryffindors, and 4 Hufflepuffs, and it would be strange if there were significantly more than eight Gryffindors — how could any of them have avoided being mentioned throughout the six years that Harry was at school with them? As there are at least 8 Gryffindors in these classes, there are at most, therefore, twelve Hufflepuffs and Slytherins.
To make up the thirty-one students in Harry’s Defense class in OotP, therefore, there must have been either 21-23 Ravenclaws and 8-10 Gryffindors, or a class made up of three or four of the houses, including Gryffindor. There is no evidence in the book either way — all the characters referred to in this scene are Gryffindors — but it seems… implausible, to say the least, that there would be a class made up of three of the houses but excluding the fourth. Thus, Harry’s OotP class either contains 20+ Ravenclaws, for a total of around fifty students in the year, or 31 students from all houses. (A third possibility is that there were originally more than 31 students from the four houses combined, but a significant number either have left Hogwarts, were ill on that day, or had heard how Umbridge taught and decided to skip class. We know at least one student, Sally-Anne Perks, had left by the end of OotP, and she could bring the total original number of students in Harry’s year up to 32, but that still seems to be on the low side.)
However, no matter how we deal with the Defence class in OotP, it can’t be used to justify Harry’s year being bigger than 56 students (8 Gryffindors, 12 Slytherins and Hufflepuffs, 23 Ravenclaws, Sally-Anne Perks leaving before 5th year). If that’s a normal sized year, then Hogwarts would have about 400 students, which is higher than the smallest possible number of students, but doesn’t even approach 600, let alone 1,000.
Equally, there is evidence that the school is relatively small overall, or that Harry’s year is not abnormally sized:
There only appears to be one teacher for each subject. Harry is always taught by the same teachers except when it is explicitly stated that they leave the school, and the teachers at the High Table in PS/SS are all ones of which we know from other sources. If there were more than two class groups per year, there would not be enough teachers. There is a little bit of play here — in muggle schools in the UK, the standard class size is closer to 30, so the school could be 50% bigger than the 280 Harry’s year would imply. But we still cannot get close to 600 this way.
There is also evidence compatible with the small school hypothesis which is also compatible with larger population estimates:
“About a hundred owls” appear at breakfast every morning.[PS101] We know that this isn’t only those owls which have post, because Harry observes that though he hasn’t yet had any post, Hedwig often comes to see him and be fed bacon. Though we don’t know what proportion of the students have owls, this is certainly compatible with there being a relatively small number of students.
Harry sees “hundreds of faces” in the Great Hall at the sorting feast.[PS87] If there were many more than one thousand, he would probably say “thousands of faces”, but this is compatible with both big- and small-school suggestions.
Some evidence, though, appears to argue for a significantly larger school population:
Firstly, in PoA ch. 15, there are 200 Slytherin supporters at the Slytherin-Gryffindor quidditch match. As “three quarters of the crowd” were said to be wearing Gryffindor colours, the crowd must be around 800 strong. Even assuming that the “two hundred” Slytherin supporters is only accurate to a single significant figure, there must be at least 600 people in the crowd. It seems implausible that fully half the crowd are not students, even if we accept that Quidditch is a massively popular sport and that the entire school has turned out to watch this match rather than being in detention, having too much homework, not liking Quidditch, or one of a myriad of other reasons that one might not want to turn up to the match. The size of the crowd can fit with the small-school hypothesis, but it is more likely that the student body is in fact over three hundred based on this one scene.
Secondly, the thestral-drawn carriages which carry the second to seventh years to the school from the station are said to number “at least a hundred”[PoA68]. They can fit at least five students in[OotP179]. Their capacity is then at least 500, and at least once the carriages have fewer than five people in them — there are only four in Harry’s carriage in Goblet of Fire[GoF151]. All, or almost all, of the carriages must be used, as Draco and his friends are forced to kick some second years out of a carriage in OotP[OotP178] in order to get a carriage to themselves. We don’t know what the average number of students in a carriage is, but we never see fewer than four students in a carriage, which argues that there are 400+ students excluding first years, or on average 66.6 students per year, totaling almost 470 students. This is still not close to the 600 or 1,000 that JKR suggests, but is significantly bigger than the lowest estimates of <300. (Hogwarts' maximum capacity, going by the thestral-carriages, might be as much as 700, if six students can fit in each carriage).
In the pensieve memories that Harry sees in OotP ch.28, we see the Marauders’ year group sit their Defence OWL. Harry sees that there were “more than a hundred”[OotP564] students in the examination hall, which taken at face value suggests that there were more than 100 students in James Potter’s year, and therefore more than 700 students in the school during the Marauders’ Era. While populations do change over the course of a generation, this seems like a huge change — the school population must have halved between James’ and Harry’s generations.
Later in OotP, we discover that when Harry and co sit their written OWLs, they do so with a NEWT class at the same time. This is perfectly compatible with real-life examination procedure, where frequently multiple different exams are taken together in the same room — it saves on invigilators, if nothing else. This was probably also the case when James Potter took his OWLs.
We don’t know which exam(s) the Marauder Era defence OWL was shared with, nor do we know how many more than a hundred there were in the exam room at the time — Harry is as terrible at estimating quantities as his creator is — but it could easily be the case that there were 60 OWL students and as many as 50 NEWT students for a popular NEWT — there are only 12 NEWTS apparently offered, after all, and most students choose at least 5 out of the 8 or 9 OWL subjects they usually do. When we consider that some NEWT subjects are almost certainly virtually empty — History of Magic, for instance, or Muggle Studies — this is perfectly believable.
On the other hand, there could be a smaller NEWT subject in the room, in which case 90 or more of the students could be in the Marauders’ year. This is not, however, compatible with any of the other evidence in canon. 50-60 students in James Potter’s year is perfectly compatible with this evidence, and so continues to be the most likely population of Hogwarts.
There is absolutely no evidence in the books that at the time that Harry was at Hogwarts, the school had even close to 1,000 students in residence. Nor is there any evidence that the school has the capacity for 1,000 boarders — there aren’t enough thestral-drawn carriages, and there aren’t even close to enough teachers. The highest population estimate one can come up with seems to be 800 from the Quidditch match in PoA, assuming that there are no spectators from outside Hogwarts and that Harry’s estimate of 200 Slytherins is accurate.
The minimum possible population estimate of 280, assuming forty in Harry’s year and this being typical, seems to be too low. Not only does it ignore the evidence from Harry’s Defence class in OotP, it would imply that there were on average only 2.5 students in each thestral-drawn carriage, which seems unlikely. It would also necessitate at minimum 320 spectators at the Quidditch match, or 15% more non-students than students, assuming a 100% turn out. The more accurate we assume Harry’s estimate of the turn out to be, the more unlikely this requirement becomes. (That’s not to say that it is impossible: the Oxford-Cambridge Boat Race, to take an extreme example, had 7.3 million watch it on television in 2013, and an estimated 200,000 go to watch it live — vs. around 40,000 students from the two institutions combined. This is clearly an extreme example, but Quidditch is a significantly more popular sport in the Wizarding world than rowing is in the Muggle world, and a higher proportion of British witches and wizards seem to have ties to Hogwarts than British Muggles do to Oxbridge.)
There is some reason to make a case that Harry’s year is exceptionally small, and that the normal population of Hogwarts is somewhat above 500. The most cogently argued essay to put Hogwarts’ student population in the 500-700 range that I have read is here. The thestral-drawn carriages and the quidditch supporters in PoA both point in this direction.
Even the smallest estimate of the medium-Hogwarts crowd at ~500 students during Harry’s time there seems extremely implausible, however. There cannot be more than one Defence teacher at Hogwarts — we are told multiple times that no defence teacher has stayed at Hogwarts for more than a year throughout Harry’s time there, and there has never been more than one teacher introduced — and yet one teacher would struggle to teach the ten classes of 35 students that this would require from years 1-5, let alone the NEWT classes on top of this. At best, students could expect to receive 2 hours of teaching per week in a core subject, even during their NEWT years. By contrast, A-level students in England, studying 3-4 subjects, receive around 5 hours per week. Even accepting that more NEWTs tend to be taken than A-Level equivalents — 5 appear to be standard, vs. the three which is common for A-levels — Hogwarts students must be significantly undertaught compared to their muggle counterparts.
I simply cannot believe that there can have been any more than 420 students at Hogwarts during Harry’s time there — Harry’s year being on the small side with only 50 students, and a more typical year having about 60. The canonical evidence seems to point to a number squarely between 350 and 420, and there’s simply no way that the school as it is described could have accomodated many more students than that. The PoA Quidditch match must be explained by a combination of Harry possibly overestimating the number of spectators, and amateur Quidditch fans and students’ relatives coming to fill out the stands’ numbers from around 300-400 to 600 or more. It seems implausible, but it is the only way to make the numbers work, and depending on how popular amateur Quidditch is, and the size of the wizarding population as a whole, it is eminently possible for a key match. The thestral-drawn carriages are in fact compatible with a much smaller school than the 5-600 that they make possible — nothing says that all of the carriages were full, just that all of them were in use. The carriages must have had on average 3 to 3.5 students in them, which is perfectly believeable.