How many students attended Hogwarts?

Question

While re-listening to Harry Potter and the Prisoner of Azkaban (audiobook), I noticed that after Sirius tried to get into the Gryffindor common room, and everyone goes to the Great Hall, Dumbledore only creates hundreds of sleeping bags, implying less than 1000 students. Is there any way to know how many students attended Hogwarts, or how many students are in each house?

Answer 1

This is a surprisingly difficult question to answer.

J. K. Rowling once said in an interview that

there are about 1000

Yet, this analysis concluded that there are around 280. This count is based on what the films show.

You can also try this reddit thread which discusses this question.

Finally though, I'll paste a small part of this interview here. These are J. K. Rowling's own words:

Then I've been asked a few times how many people and because numbers are not my strong point, one part of my brain knew 40, and another part of my brain said, “Oh, about 600 sounds right.” Then people started working it out and saying, "Where are the other kids sleeping?"

So the answer is somewhere between 280 and 1000, but the common number seems to be the lower.

Answer 2

Like many things in the series, there seems to be various different lines of evidence that don't all necessarily lead to the same conclusion. It should be kept in mind that there is not necessarily a reason why there should or would be the same amount of students from one year to the next.

General Statements

That said, throughout the series there are consistent indications that there are somewhere between several hundred to a thousand students. These indications come in the form of a couple dozen quotes describing some aspect of the Hogwarts population. Most of the quotes are simply various reiterations of "hundreds of students walking around" or something similar. I don't think that fewer than 300 people would be described as "hundreds". Sometimes it even says "hundreds upon hundreds" which would imply even more students. All those quotes are collected at the end of this post so as not to burden the reader.

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In addition to the above general descriptions there are some specific quotes that can give us a more precise estimate:

Carriage Capacity

For instance, there are approximately 100 Thestral carriages, as per Order of the Phoenix Chapter 10:

Here stood the hundred or so horseless stagecoaches that always took the students above first year up to the castle.

We usually see something like 4 or 5 students in a carriage, but a passage in the same chapter of Order of the Phoenix indicates that there may have been even 6 or more:

A short distance away, Draco Malfoy, followed by a small gang of cronies including Crabbe, Goyle, and Pansy Parkinson, was pushing some timid-looking second years out of the way so that they could get a coach to themselves.

So there could be something like 500 or more seats for everyone except the first years.

Yule Ball Attendees

We see in Goblet of Fire Chapter 23 by the Yule Ball that there were approximately 100 small tables that seat 12 apiece:

The House tables had vanished; instead, there were about a hundred smaller, lantern-lit ones, each seating about a dozen people.

Even if they wouldn't be filled to capacity, and subtracting the guests, there could easily be 800 students at Hogwarts (especially considering that anyone third year and below who did not have an older date could not attend.) In fact, as we find out in Chapter 22, one of the rumors was that Dumbledore ordered 800 barrels of mulled mead:

The last week of term became increasingly boisterous as it progressed. Rumors about the Yule Ball were flying everywhere, though Harry didn’t believe half of them — for instance, that Dumbledore had bought eight hundred barrels of mulled mead from Madam Rosmerta.

Even if the rumor is not true, as Harry suspected, there would have to be enough people in the castle for such an order to be even conceivable.

O.W.L. Students

We also find in Order of the Phoenix Chapter 28 that when Snape took his O.W.L.s there were over 100 tables, each with one student:

He was standing in the middle of the Great Hall, but the four House tables were gone. Instead there were more than a hundred smaller tables, all facing the same way, at each of which sat a student, head bent low, scribbling on a roll of parchment.

That means that there were more than 100 students just in the fifth year, which could easily translate into 600-800 students in total.

Quidditch Spectators

Perhaps the most precise evidence comes from the number of spectators at the Quidditch match in Prisoner of Azkaban Chapter 15. It is described as 3/4 supporting Gryffindor and 200 supporting Slytherin:

Three-quarters of the crowd was wearing scarlet rosettes, waving scarlet flags with the Gryffindor lion upon them, or brandishing banners with slogans like “GO GRYFFINDOR!” and “LIONS FOR THE CUP!” Behind the Slytherin goal posts, however, two hundred people were wearing green; the silver serpent of Slytherin glittered on their flags, and Professor Snape sat in the very front row, wearing green like everyone else, and a very grim smile.

This would mean that there were roughly 800 people attending the match, and throughout the series it seems as if the entire school usually comes to Quidditch matches. If we subtract a few staff members, this would put the total number of students at slightly less than 800.

Gryffindor Quidditch Trials

When Harry holds the trials for the Gryffindor Quidditch team in the beginning of Half-Blood Prince, his perception is:

Half of Gryffindor House seemed to have turned up

We can attempt to figure out approximately how many people are in Gryffindor by seeing how many people were at the trials and then multiplying by two.

We start off with 50 applicants, as Harry divided them into groups of ten and there were at least five groups:

Harry decided to start with a basic test, asking all applicants for the team to divide into groups of ten and fly once around the pitch.

The fifth group were Hufflepuffs.

Then there were a couple of Ravenclaws:

There was a pause, then a couple of little Ravenclaws went sprinting off the pitch, snorting with laughter.

Then there were the seven actual members of the team, as well as everyone else who actually did a tryout. This presumably was not a small number, because it took two hours before they even got up to the Keeper tryouts:

After two hours, many complaints, and several tantrums

The many complaints and several tantrums were presumably all from people who didn't make the team. At the very least, we know for a fact that there were six additional Keeper applicants besides Ron:

None of the first five applicants saved more than two goals apiece. To Harry's great disappointment, Cormac McLaggen saved four penalties out of five.

Thus, there were at least 65 students there, and likely many more. Therefore Gryffindor can be presumed to have at least 130 students, though possibly many more. If there is an even distribution among houses then there would have to be well over 500 students in the school.

Defense Against the Dark Arts Class (Fifth Year)

Throughout the series I don't think we ever find Harry having Defense Against the Dark Arts with another house (not counting N.E.W.T classes where everyone seems to be together because there are so few students). Yet in the first Defense Against the Dark Arts Class in *Order of the Phoenix Harry seems to have 30 classmates:

"It was murder," said Harry. He could feel himself shaking. He had hardly talked to anyone about this, least of all thirty eagerly listening classmates. "Voldemort killed him, and you know it."

This means that there are 30 students in one year of one house. This certainly does not accord with the conservative theory that there are 10 students per year per house for a total of 280 students. It would however be consistent with a much higher estimate of 800 or more students.

Divination Class

The first time Harry goes to Divination we get the following description of the classroom:

At least twenty small, circular tables were crammed inside it, all surrounded by chintz armchairs and fat little poufs.

And it wasn't even one person per table:

Harry, Ron, and Hermione sat themselves around the same round table.

Thus, the classroom can seemingly accommodate 60 students. And this is in an elective class, where (at least for Harry's year) it is taught to Gryffindor alone. Even if all the tables were not filled to capacity, the very fact that the classroom has that many seats should indicate the potential for a class to be around that size. According to the conservative estimate of number of students in the school, even if all four houses had class together and every student took Divination the classroom would only be two thirds full. Therefore, it stands to reason that there are actually many, many, many more students in the school.

Flying, Herbology, Potions, and Care of Magical Creatures Class

On the other hand, in Harry's Herbology class with Hufflepuff in Chamber of Secrets Chapter 6 there appear to be only 20 students (based on the 20 pairs of earmuffs):

About twenty pairs of different-colored ear-muffs were lying on the bench.

Likewise, his flying class with Slytherin in Philosopher's Stone Chapter 9 also only has 20 students (based on the 20 broomsticks):

The Slytherins were already there, and so were twenty broomsticks lying in neat lines on the ground.

Likewise, his Potions class with Slytherin in Chamber of Secrets Chapter 11 also only has 20 students (based on the 20 cauldrons):

Twenty cauldrons stood steaming between the wooden desks, on which stood brass scales and jars of ingredients.

Similarly, Harry's third year Care of Magical Creatures class with the Slytherins appears to have only had about 20-30 students. In the first lesson we are told that there were a dozen hippogriffs:

Trotting toward them were a dozen of the most bizarre creatures Harry had ever seen.

And we later find 1-3 students per hippogriff:

Neville ran repeatedly backward from his, which didn't seem to want to bend its knees. Ron and Hermione practiced on the chestnut, while Harry watched.

Malfoy, Crabbe, and Goyle had taken over Buckbeak.

The number of students in these classes would seem to indicate that the school is much smaller (only a couple hundred students or so).

To address these small numbers one could perhaps suggest that Ravenclaw got 50% or more of the students in Harry's year – which would explain why Gryffindor has classes with Hufflepuff and Slytherin but never with Ravenclaw (not counting N.E.W.T. classes where all the houses are combined due to the small number of students advancing) – but Ravenclaw does not appear to be overly represented from the (part of) the sorting we see (in which they got three students). Alternatively, Harry's year might be particularly small and the rest of the school had all the hundreds of students, but there does not seem to be any particular evidence for this.

Defense Against the Dark Arts Class (Sixth Year)

In Harry's sixth year his N.E.W.T Defense Against the Dark Arts class is taught to all four houses together. This can be demonstrated as follows:

We know Slytherin was there, by the presence of Malfoy:

"An answer copied almost word for word from the Standard Book of Spells, Grade Six," said Snape dismissively over in the corner, Malfoy sniggered), "but correct in essentials.

We know Hufflepuff was there, by the presence of Ernie Macmillan:

"Harry," Ernie said portentously, holding out his hand as Harry approached, "didn't get a chance to speak in Defense Against the Dark Arts this morning.

We know Ravenclaw was there based on the following calculation:

In one class, Snape collects their essays and we see that there are 25 of them:

"Before we start, I want your Dementor essays," said Snape, waving his wand carelessly, so that twenty-five scrolls of parchment soared into the air and landed in a neat pile on his desk.

In the first class, we find out that at least half the class had been D.A. members:

Although Snape did not know it, Harry had taught at least half the class (everyone who had been a member of the D.A.) how to perform a Shield Charm the previous year.

This means that there were at least 13 D.A. members in Harry's year. If we go back to the original D.A. gathering in Order of the Phoenix we are given a complete list of the 28 members:

1. Harry
2. Hermione
3. Ron
4. Neville
5. Dean
6. Lavender
7. Parvati
8. Padma
9. Cho
10. One of Cho's friends (Marietta)
11. Luna
12. Katie
13. Alicia
14. Angelina
15. Colin
16. Dennis
17. Ernie
18. Justin
19. Hannah
20. Hufflepuff girl Harry didn't yet know (Susan Bones)
21. Anthony Goldstein
22. Michael Corner
23. Terry Boot
24. Ginny
25. Tall skinny blond boy (Zacharias Smith)
26. Fred
27. George
28. Lee

As you can see from the bolded names, there were only eleven members of the D.A. in Harry's year that were not in Ravenclaw. Thus, in order for at least half of Harry's Defense Against the Dark Arts class to have been in the D.A. the class must have included Ravenclaw as well.¹

We can therefore conclude that the total number of students in Harry's year (all four houses) that advanced to N.E.W.T. Defense Against the Dark Arts was 25. It seems somewhat unlikely that more than half the year was unable to advance to N.E.W.T. Defense Against the Dark Arts, so that would put the total number of students in Harry's year at somewhere below 50. Assuming even distribution between years, this would be pretty consistent with the most conservative estimates of total number of students – a couple hundred or so.

Knowing Fellow Students

But if indeed there were only a couple hundred students you might expect Harry to at least have a passing familiarity with most, if not all, of them. Yet throughout the series Harry routinely passes by or interacts with students that he does not seem to know at all. In fact, he doesn't learn Susan Bones's name until Order of the Phoenix Chapter 16, which is after presumably having 4 1/2 years of classes with her:

and a Hufflepuff girl with a long plait down her back whose name Harry did not know;

“Is it true,” interrupted the girl with the long plait down her back, looking at Harry, “that you can produce a Patronus?”

There was a murmur of interest around the group at this.

“Yeah,” said Harry slightly defensively.

“A corporeal Patronus?”

The phrase stirred something in Harry’s memory.

“Er — you don’t know Madam Bones, do you?” he asked.

The girl smiled.

“She’s my auntie,” she said. “I’m Susan Bones. She told me about your hearing. So — is it really true?

If there are only 20 students per class that would be very strange. If there were 50-100 or more students in a class it would make sense.

In the same scene we see that Harry barely knows the names of Terry Boot, Anthony Goldstein, and Michael Corner who are all in his year, and doesn't know Zacharias Smith's name at all:

three Ravenclaw boys he was pretty sure were called Anthony Goldstein, Michael Corner, and Terry Boot; Ginny, followed by a tall skinny blond boy with an upturned nose whom Harry recognized vaguely as being a member of the Hufflepuff Quidditch team,

Ron as well clearly did not know Michael Corner or Zacharias Smith:

“Who are you?” said Ron rather rudely.

“Zacharias Smith,” said the boy, “and I think we’ve got the right to know exactly what makes him say You-Know-Who’s back.”

“Which one was Michael Corner?” Ron demanded furiously.

“The dark one,” said Hermione.

Likewise, Harry does not know Cormac McLaggen in the beginning of Half-Blood Prince, despite them being in the same house and only one year apart.

there were also two seventh-year boys Harry did not know

"This is Cormac McLaggen, perhaps you've come across each other – ? No?"

This means that Harry does not know someone whom he has been sharing a common room with for five years. This might be understandable if there were upwards of 200 students in a house; less so if there were only 70 students in a house.

Similarly, Harry does not know Romilda Vane until she introduces herself to him on the Hogwarts Express in Half-Blood Prince... after sharing a common room with her for four years:

Before he could respond, however, there was a disturbance outside their compartment door; a group of fourth-year girls was whispering and giggling together on the other side of the glass.

"You ask him!"

"No, you!"

"I'll do it!"

And one of them, a bold-looking girl with large dark eyes, a prominent chin,and long black hair pushed her way through the door.

"Hi, Harry, I'm Romilda, Romilda Vane," she said loudly and confidently.

Even Hermione apparently doesn't know a girl she's been sharing a common room with for more than five years:

Hermione hurried over to Katie's wailing friend and put an arm around her.

"It's Leanne, isn't it?"

Conclusion

Most likely, J.K. Rowling either didn't think it through enough, or just messed up on the calculations, because there are several passages that imply a relatively small number of students yet there is also significant evidence that the total is a lot more than that.

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General Quotes

Philosopher's Stone Chapter 7

They followed Professor McGonagall across the flagged stone floor. Harry could hear the drone of hundreds of voices from a doorway to the right — the rest of the school must already be here — but Professor McGonagall showed the first years into a small, empty chamber off the hall.

Ibid

The hundreds of faces staring at them looked like pale lanterns in the flickering candlelight.

Philosopher's Stone Chapter 10

Hundreds of seats were raised in stands around the field so that the spectators were high enough to see what was going on.

Chamber of Secrets Chapter 8

A rumble, as though of distant thunder, told them that the feast had just ended. From either end of the corridor where they stood came the sound of hundreds of feet climbing the stairs, and the loud, happy talk of well-fed people; next moment, students were crashing into the passage from both ends.

Chamber of Secrets Chapter 16

They hid themselves inside it, listening to the rumbling of hundreds of people moving overhead, and the staffroom door banging open.

Prisoner of Azkaban Chapter 5

Harry, Ron, and Hermione followed the rest of the school along the platform and out onto a rough mud track, where at least a hundred stagecoaches awaited the remaining students, each pulled, Harry could only assume, by an invisible horse, because when they climbed inside and shut the door, the coach set off all by itself, bumping and swaying in procession.

Prisoner of Azkaban Chapter 9

One casual wave of his wand and the long tables flew to the edges of the hall and stood themselves against the walls; another wave, and the floor was covered with hundreds of squashy purple sleeping bags.

Goblet of Fire Chapter 15

Hundreds upon hundreds of owls of every breed imaginable were nestled here on perches that rose right up to the top of the tower, nearly all of them asleep, though here and there a round amber eye glared at Harry.

Goblet of Fire Chapter 17

It felt like an immensely long walk; the top table didn’t seem to be getting any nearer at all, and he could feel hundreds and hundreds of eyes upon him, as though each were a searchlight.

Ibid

Harry heard the buzzing of the hundreds of students on the other side of the wall, before Professor McGonagall closed the door.

Ibid

Yet how could anyone think that, when he was facing competitors who’d had three years’ more magical education than he had — when he was now facing tasks that not only sounded very dangerous, but which were to be performed in front of hundreds of people?

Goblet of Fire Chapter 19

Admittedly, he didn’t see how Sirius was going to make him feel any better about having to perform an unknown piece of difficult and dangerous magic in front of hundreds of people, but the mere sight of a friendly face would be something at the moment.

Goblet of Fire Chapter 20

And in no time at all, hundreds upon hundreds of pairs of feet could be heard passing the tent, their owners talking excitedly, laughing, joking. ... Harry felt as separate from the crowd as though they were a different species.

Ibid

There were hundreds and hundreds of faces staring down at him from stands that had been magicked there since he’d last stood on this spot.

Ibid

Harry waited, every fiber of him hoping, praying. ... If it hadn’t worked ... if it wasn’t coming ... He seemed to be looking at everything around him through some sort of shimmering, transparent barrier, like a heat haze, which made the enclosure and the hundreds of faces around him swim strangely. ...

Goblet of Fire Chapter 31

Five minutes later, the stands had begun to fill; the air was full of excited voices and the rumbling of feet as the hundreds of students filed into their seats.

Order of the Phoenix Chapter 12

With a whoosh and a clatter, hundreds of owls came soaring in through the upper windows.

Ibid

The bell rang for the end of the lesson. Overhead and all around came the elephantine sounds of hundreds of students on the move.

Order of the Phoenix Chapter 14

The sun was high in the sky now and when Harry entered the Owlery the glassless windows dazzled his eyes; thick silvery beams of sunlight crisscrossed the circular room in which hundreds of owls nestled on rafters, a little restless in the early morning light, some clearly just returned from hunting.

Order of the Phoenix Chapter 19

They could hear hundreds of footsteps mounting the banked benches of the spectators’ stands now.

Half Blood Prince Chapter 8

With the usual deafening scraping noise, the benches were moved back and the hundreds of students began to file out of the Great Hall toward their dormitories.

Half Blood Prince Chapter Chapter 18

He could only suppose that he was missing Malfoy amongst the hundreds of tiny black dots upon the map.

Half Blood Prince Chapter 19

“Gotta see it from their point o’ view,” said Hagrid heavily. “I mean, it’s always bin a bit of a risk sendin’ a kid ter Hogwarts, hasn’ it? Yer expect accidents, don’ yeh, with hundreds of underage wizards all locked up tergether, but attempted murder, tha’s diff’rent.

Deathly Hallows Chapter 30

“Potter, we’re talking about hundreds of students — ”

Deathly Hallows Chapter 31

The sound of hundreds of people marching toward the Room of Requirement grew louder and louder as he returned to the marble stairs.

Ibid

“I’ve had hundreds of kids thundering through my pub, Potter!”

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^{1. This may not be entirely accurate. Even though there were only 11 non-Ravenclaws in Harry's year at the original DA meeting, we know that at least one such person joined subsequently. In Chapter Twenty-Seven of Order of the Phoenix we find the following:}

^{“Harry, I think I’m doing it!” yelled Seamus, who had been brought along to his first ever D.A. meeting by Dean.}

^{Thus, one could argue that Seamus was also taught the Shield Charm the previous year, thus making 12 non-Ravenclaws (in Harry's year) in total.}

^{However, there are a couple of counterpoints to this. First of all, Harry had taught the Shield Charm before Seamus joined; this is clear from it being mentioned in Chapter Twenty-Five of Order of the Phoenix, two chapters prior to Seamus joining:}

^{He was improving so fast it was quite unnerving and when Harry taught them the Shield Charm, a means of deflecting minor jinxes so that they rebounded upon the attacker, only Hermione mastered the charm faster than Neville.}

^{One could perhaps suggest that at a later meeting (after Seamus joined) they reviewed Shield Charms, and therefore Seamus could be counted as the thirteenth member of the class who already knew how to do a Shield Charm. However this brings us to the second counterpoint which is that even if we count Seamus we would still only have 11 since we counted Harry as one of the 12, though Harry would not actually be considered as part of the half of the class that he had taught the previous year.}

^{It would seem, then, that we are still missing one person, in which case we would have to concede that the half of the class threshold was met using Ravenclaws.}

Answer 3

There hasn't been a canon answer to this that I know of, and JKR has repeatedly admitted that she is bad at math.

The most popular answer that is out on the web is extrapolated from the number of boys and girls in Harry's class (10), multiplied by # of years (7) and number of houses (4) to get 280.

However, in Order of the Phoenix when Harry goes into Snapes memories of the OWL testing, we get this quote (emphasis mine):

‘Quills down, please!’ squeaked Professor Flitwick. ‘That means you too, Stebbins! Please remain seated while I collect your parchment! Accio!’

Over a hundred rolls of parchment zoomed into the air and into Professor Flitwick’s outstretched arms, knocking him backwards off his feet. Several people laughed. A couple of students at the front desks got up, took hold of Professor Flitwick beneath the elbows and lifted him back on to his feet.
_{Harry Potter and the Order of the Pheonix, chapter 28: "Snape's Worst Memory"}

So if there are over 100 rolls of parchment, we can get the number of students taking their OWL's that year as somewhere between 100 and 200. That would put the number of students at Hogwarts as in the range of 700 - 1400 (Only multiply by the number of years, as an OWL test would have all houses.

The other thing to consider is that Harry's year is the first year with kids born since the Wizarding War, and during the war birthrates would have dropped. This would make Harry's class artificially low from the average (not including Muggleborns).

So on the low side, you have 280, on the high side 1400, with variances for birth rates and outside influences.