How Many Harry's Are There? An Essay on the Population of Wizarding Britain

There are many intriguing questions to be raised about the magical world in which Harry Potter finds himself upon reaching his eleventh birthday. How many wizards and witches lived in Britain when Harry Potter went to school? What do different possibilities for the Hogwarts population imply about the size of the wizarding world? This essay will attempt to answer one subset of questions: how many wizards and witches lived in Britain when Harry went to school, and how might different population estimates for Hogwarts affect these figures? These questions will be answered based on canon references in the books, and supplemented by interviews and comments by J.K. Rowling (with most references coming from the Harry Potter Lexicon).

It must be stressed from the outset that this essay can only derive tentative estimates without further canonical information; only educated guesses are possible. Moreover, these guesses must be built from a series of assumptions, which will be underlined in the text to draw attention to them. While reasonable, any one of these dependencies might be incorrect, in which the entire estimate could become wildly inaccurate. It is also worth noting that Rowling admits to difficulty with mathematics, thus her estimates (both within and without the books) are subject to a significant grain of salt. With that in mind, let us lay out the assumptions which are the foundation of this essay's hypothesis.

Assumptions and Extrapolations I: The Age of Wizards

Determining the size of the wizarding world in the mid-1990s requires extrapolations of numerous quantities, including the population of Hogwart's School, the number of children had by magical families, and the like. However, the most fundamental variable here is the estimated life expectancy of wizardkind, as it stood when Harry Potter arrived in Diagon Alley.

We know from J.K. Rowling that wizards (which I will use as shorthand for wizards and witches from here on out, with apologies) live significantly longer than Muggles. She has stated this in interviews, and it is also evident from the books themselves. Let us examine the information in the canon first.

We know that Albus Dumbledore is extremely old. J.K. Rowling said that he was 150 years old in a 2001 BBC interview, but according to the January 2007 Wizard of the Month feature on her website, Dumbledore was born in 1881, making him nearly 116 years old when he was killed by Severus Snape in 1997. Minerva McGonagall is stated to be at least 70 years old by Rowling. If, as the HPL suggests, she was born in 1925, she was almost 73 years old by the time of the events in Deathly Hallows, and yet she is still a working professor (and deputy Headmistress until at least the Half Blood Prince). She retired from the post of Headmistress, according to post-DH Rowling interviews, between the end of Deathly Hallows, and the epilogue, set in 2017 (at which point McGonagall would have been 92). According to HPL, Rubeus Hagrid was born in December 1928, just three years after McGonagall.

Aside from Hogwarts professors, there are plenty of other examples of long-lived wizards in Britain. Elphias Doge, for example, is a contemporary of Dumbledore's (as an article about Rowling's outing of Dumbledore speculates, they might even have been intimate), and he is still alive and writing obituaries for Dumbledore, and Aberforth Dumbledore brother, only slightly younger than Albus, is active, as well. Likewise, we know that a Professor Marchbanks arrived at Hogwarts in 1996 to test fifth-year students on their OWLs (during Order of the Phoenix), and we know that she tested Dumbledore for his NEWTs, so she is at least a few years his senior. She was very aged at the time of OOTP, but still alive and energetic enough to reprimand Umbridge. Finally, we know that Gellert Grindelwald, who was just two years younger than Dumbledore also was still alive until 1998, despite being imprisoned for more than fifty years. or so many aged wizards to still be playing key roles in events of national importance - not to mention engaging in strenuous events like battles, we can see direct proof that wizards are indeed much longer-lived than Muggles. This is partially countered by Rowling's chart, called "The Most Noble and Ancient House of Black," which does not seem to indicate that wizards live unusually long lives. This document must, however, be set aside in the face of more direct canon evidence, as well as Rowling's own statements on the subject.

As of 1995, census figures from the United Kingdom show that the average life expectancy was 76.2 years (this is a real-life statistic, and thus excludes magical persons). If we know that wizards live "much longer than Muggles," and we see so many examples of wizards active well into their seventies, then the first assumption can be made. For the purposes of this essay, it will be assumed that the life expectancy of a British wizard in 1995 was 95 years. This is nearly 20 years longer than the average for Muggles in the same time period, or about 25 percent greater than the UK national average. This seems to be a reasonable interpretation of "much longer than" non-magical persons, although it could easily be a decade high or low.

Assumptions and Extrapolations II: The Bell-Curve of Wizards

From the estimate of a wizard's lifespan, we can now construct a rough estimate of the Wizarding population's age distribution, based on existing census data from the British government. Printed below is a chart of the 1995 UK population, grouped by age, and based on a government bar graph (the numbers are rounded for convenience).

UK POPULATION DISTRIBUTION, 1995:

Men: Women: Combined:

0-4: 1.95m 1.85m 3.8m

5-9: ~2.0m 1.9m 3.9m

10-14: 1.9m 1.75m 3.75m

15-19: 1.8m 1.8m 3.6m

20-24: 2.05m 1.95m 4.0m

25-29: 2.35m 2.25m 4.6m

30-34: 2.4m 2.3m 4.7m

35-39 2.1m 2.05m 3.15m

40-44: 1.9m 1.9m 3.8m

45-49: 2.05m 2.05m 4.1m

50-54: 1.65m 1.65m 3.3m

55-59: 1.5m 1.5m 3.0m

60-64: 1.35m 1.45m 2.8m

65-69: 1.25m 1.4m 2.65m

70-74: 1.1m 1.4m 2.5m

75-79: 0.7m 1.05m 1.75m

80+: 0.7m 1.6m 2.5m

28.75 million 29.85 million

58.6 million, total

Thus, in 1995, the total population of the United Kingdom was approximately 58,600,000 persons, with an average overall life expectancy of 76.2 years. By doing some quick division to produce a rough subdivision by year of the 75-79 bracket, we can determine the percentage of the UK population that is aged 76 or above, that is, above the national life expectancy. This shows that approximately 6.65 percent of the total British population, at any given time, are above the average life expectancy (of course, 50% of people live longer than the average expectancy, but the number of people who are that age at any given time is 6.65%).

If wizards live to an average age of 95 years, then we may assume that a similar percentage of the wizarding population as a whole exceeds the 95-year expectancy. This is the second conclusion required to compute the wizarding population, and it is probably the most well-grounded assumption of the lot.

Based on this, we can begin to construct a rough estimate for how the wizarding world's age distribution chart would appear, and how it would differ from that of the larger (Muggle) UK population. Life expectancy statistics are always assessed from birth, and they account for many possible illnesses, birth defects, and injuries to which the young are especially vulnerable. Thus, a person who reaches the age of majority can be expected to live past the notional life expectancy. Likewise, some older individuals will be more resilient than others of their age, so they may live well beyond the life expectancy of the country, even while their contemporaries succumb. For this reason, it appears that the ends of the population curve (in deaths) are more pronounced; that is, more people will die in infancy, childhood, or old age, than will die in middle age, when the body's strength is greatest. Only accidents, exceptionally severe illnesses, or violent acts can be expected to claim the lives of most middle-aged persons in reasonable health.

We will therefore assume that wizarding children succumb to birth defects, illnesses, household injuries, and attacks by violent creatures and plants in roughly the same proportion as Muggle children, and that elderly wizards succumb to old age, or complications of aging (either illness or injury) in the same proportion as Muggle pensioners.

Bear in mind that the population chart for wizards must accommodate an additional 20 years worth of life expectancy. Because the population vulnerability is greatest at the lower and higher extremes, we may assume that it is in the middle that the population levels will be essentially flat. This is a more precarious assumption than the others: birthrates in every year determine, at any given point, how a population chart will appear. This explains the surge in births following the Second World War, and its subsequent distortions of population charts. Aside from war, economic factors, medical advances, and changing social mores also determine birthrates. It cannot be stated with any certainty that the wizarding world would conform to the same cycles in this regard as the general population, but there is simply no other convenient way of building a population distribution chart - the cornerstone of any population estimate - without making such an assumption.

For the purposes of this estimate, an additional "block" of years is inserted into the Muggle population chart in order to produce the wizarding equivalent. For this assumption, the population figures for 35-50 year-olds were repeated, more or less, so that an extrapolated quantity (if all the UK population were wizards) of 4.0 million was assigned to each population bracket between 50 and 70 years old, since this was approximately the same figure as those for 35-50 year-olds). The figures for ages 70 and above for wizards simply match the same brackets for ages 50 and above (for Muggles). This assumes that birthrates would remain relatively static over a period of years, and allows us to construct how the UK population chart would look if all Britons were wizards rather than Muggles. This is a matter of convenience; the figures will become proportional later in the essay. For now, assume that all citizens are wizards, and the effects on population size are immediately visible.

SIMULATED UK POPULATION DISTRIBUTION (IF ALL ARE WIZARDS), 1995:

0-4: 3.8m

5-9: 3.9m

10-14: 3.75m

15-19: 3.6m

20-24: 4.0m

25-29: 4.6m

30-34: 4.7m

35-39 3.15m

40-44: 3.8m

45-49: 4.1m

50-54: 4.0m

55-59: 4.0m

60-64: 4.0m

65-69: 4.0m

70-74: 3.3m

75-79: 3.0m

80-84: 2.8m

85-89: 2.65m

90-94: 2.5m

95-100:1.75m

100+: 2.5m

This assumption would increase the overall UK population by about 16 million (an increase of 27.3 percent) to 74.6 million persons.

To reach this conclusion requires several other assumptions. First, we must assume that the First Wizarding War did not have a prominent impact on the population. In the United Kingdom, 0.94% of the total UK population was killed during the Second World War (civilian deaths accounted for only 0.14% of the total population), according to source figures hyperlinked from a Wikipedia article on the war. This impact would also be somewhat mitigated by postwar baby booms. We can assume that the Second World War would impact the UK population to a greater extent than did the First Wizarding War, because Voldemort and his Death Eaters were said to operate by stealth and terror, not by massive attacks and vast battles in the streets of London's Wizarding District and Hogsmeade. Thus, the population assumptions would not be grossly distorted by the war. We can also assume that Muggle wars would have relatively little impact on the wizarding world.

Assumptions and Extrapolations III: The Children of Wizards

The first UK population chart (the authentic chart) shows us that 7.35 million Britons were between 10 and 19 years of age in 1995 (or about 12.5% of the total UK population). If we assume that birthrates were almost identical in this period, and deaths were equivalent in each age group, then we can say that 0.735 million children were age 10, 0.735 million children were age 11, and so forth. Given this assumption, we can say that about 5.145 million children would be between the ages of 11 and 17 - the ages at which one would attend Hogwarts. This figure is about 8.8 percent of the total UK population. However, the previous section showed us that we would expect to find more "middle-aged" wizards in a wizarding population. This means that, as a percentage, children would make up a smaller portion of the populace. Thus, in a world where every Briton was magical and the life expectancy was 95, the 10-19 age group would now only encompass 9.85% of the total population, and the seventy percent of these who would fall between 11 and 17 would now represent only 6.9% of the total wizarding population.

This figure makes another key assumption, which is a matter of necessity. It assumes that wizards have children at roughly the same frequency as Muggles. In the overall UK population, the average was 1.78 children per family by the first half of the 1990s, down from 2.2 per family in the 1950s. We know that Harry Potter was an only child, as was Neville Longbottom, but their parents, who were both young when they had children (the Potters died at age 21, according to the headstones in Deathly Hallows), died while they were in infancy. By contrast, the Weasleys had seven children. The Patils had at least two children. Draco Malfoy was also an only child. It may well be that the wizarding world's average number of children is slightly less than that of the UK population as a whole, but without many more charts like Rowling's depiction of the Black family tree, this cannot be determined.

Assumptions and Extrapolations IIII: Squibs and Muggleborns

The last question, before drawing conclusions, is how to regard Muggleborns and Squibs. Clearly, Squibs can live in the wizarding world, for Argus Filch is one, and he resides at Hogwarts, but we do not know if they attend the school: what, after all, would be the point, since the Hogwarts curriculum is notably short on "practical" subjects? We do know that Muggleborns enlarge the wizarding population. In Harry's year, thanks to the infamous student list that JKR flashed during a television interview, we know Hermione Granger was Muggleborn, as, apparently, were Hannah Abbott, Justin Finch-Fletchley, Terry Boot, and Kevin Entwhistle, totaling a minimum of five out of the presumed 40 students in Harry's year (12.5 percent). Rowling tells us in interviews that Muggleborns are truly of the magical world, but at some distant remove.

Thus, at some level, we must resolve the question of how many Muggleborns there are, how many Squibs are produced, and how this balances. It appears, anecdotally, that there are more Muggleborns than Squibs, but since the HP universe centers around Hogwarts, this may not be the case. It can further be presumed that Squibs cannot continue the growth of the wizarding world (that is, a child of a Squib is no wizard), but Muggleborns can. So, the for the last and perhaps most uncertain assumption, we assume that Muggleborns and Squibs roughly balance. This essay counts Muggleborns as wizards from birth, since they eventually arrive at Hogwarts, and most seem to stay within the wizarding world once they discover it.

Assumptions and Extrapolations V: The Hogwarts Population

If all of this essays assumptions (from life expectancy to birthing rates, and their corollaries) are accurate, then we are now in a position to be able to determine the size of the wizarding population as a whole. By constructing an overall population chart, we have been able to extrapolate what proportion of the overall wizarding population would be of age to attend Hogwarts (6.9 percent).

This is the key to understand the size of Wizarding Britain. If the Hogwarts population is x students, then the total Wizarding population must be y individuals. Based on the second, simulated population chart, we can determine that x = 0.069y. We are now left with one question: how many students does Hogwarts have?

Rowling has said in interviews that Hogwarts had about a thousand students, but this figure seems inflated, and may be a result of bad math. If it were true, then Harry's year would have to have about 143 students (if it were an average class size). However, all evidence, including Rowling's chart, her own statements, and depictions of classroom implements, points to 40 students in Harry's year. Rowling later revised her estimate downward, according to the Lexicon, to about 600 students. However, if Harry's year is a typical size, then Hogwarts should have just 280 students.

Several excellent essays posted on the Internet have argued the point back and forth. Some suggest that Harry's year is atypical. Because of the war, these writers say, fewer people had children, so the numbers of wizards turning 11 in 1991 was artificially low. They also point to references to the Great Hall and Quidditch games having "hundreds" of students cheering or booing. This points to either a large school, or a problem with JKR's maths. I tend to side with the small-school adherents, partially because of the canon figures and partially because of the practical implications of having a dozen-odd faculty grading a thousand essays. Nonetheless, this essay will calculate three scenarios: small Hogwarts, medium-sized Hogwarts, and large Hogwarts.

We must ask one additional question before making the calculations: how many wizarding children aged 11-17 actually attend Hogwarts, as a percentage of wizarding children in that age bracket. Goblet of Fire established that Draco Malfoy nearly went to Durmstrang, and wound up at Hogwarts only because of his mother's influence. Deathly Hallows established that nearly all wizards went to Hogwarts anyway, but while Pius Thicknesse ran the Ministry on behalf of Voldemort, Hogwarts attendance became mandatory (except for Muggleborns, who were not permitted to attend, at all). So, except under the Thicknesse regime, children usually went to Hogwarts, but some probably went abroad, and others might have been tutored at home.

Calculations and Results: How Many Wizards Are There?

With the Hogwarts questions in mind, we may now calculate the population of Wizarding Britain, based on the equation x = 0.069y.

If all school-age wizards and witches attend Hogwarts:

X Y

1000 students (JK Rowling's initial estimate) 14,493 total population in UK

600 students (JK Rowling's revised estimate) 8,696 total population in UK

280 students (based on total in Harry's year) 4,058 total population in UK

If 95% of all school-age wizards attend Hogwarts:

X Y

1000 students (JK Rowling's initial estimate) 15,224 total population in UK

600 students (JK Rowling's revised estimate) 9,135 total population in UK

280 students (based on total in Harry's year) 4,263 total population in UK

If 90% of all school-age wizards attend Hogwarts:

X Y

1000 students (JK Rowling's initial estimate) 16,103 total population in UK

600 students (JK Rowling's revised estimate) 9,662 total population in UK

280 students (based on total in Harry's year) 4,509 total population in UK

Thus, we can see that at a bare minimum, if all assumptions hold, that the wizarding population of Great Britain is at least 4,000 individuals (if Hogwarts is small, and all children attend it), and may be as high as 16,000 individuals (if Hogwarts is large, and not all school-age children attend it). This provides an interesting constraint for the wizarding population, and the scope of activities in which they might be engaged.

However, it is worth noting that the numbers are not quite as restricting as one might think, since goblins, dwarves, and house-elves are sentient magical beings, who directly interact with the wizarding world. Centaurs and mer-people, naturally, do not. Thus, jobs like servants and bankers are filled, without requiring wizards to fill them. Thus, a reasonable society, in a number of villages, may be supported by a wizarding population of 4,000-16,000.

These figures can tell us one other piece of information: how many children, within their age group, are wizards. These calculations assume that all wizarding children attend Hogwarts. Assuming that the proportions would be identical at birth as at ages 11-17, we can state the frequency of wizard births in the UK. Therefore:

If Hogwarts has 280 students, then 0.0054% of all persons born in Britain are wizards, or 1 out of every 18,375 live births.

If Hogwarts has 600 students, then 0.0117% of all persons born in Britain are wizards, or 1 out of every 8,575 live births.

Finally, if Hogwarts has 1000 students, then 0.0194% of all persons born in Britain are wizards, or 1 out of every 5,145 live births.

Using these figures, we can even come up with estimates for the wizarding populations of other countries and other times, based on 2007 population estimates:

0.0054% 0.0117% 0.0194%

France 3,441 7,455 12,361

Germany 4,450 9,641 15,986

United States 16,262 35,233 58,421

China 71,380 154,657 256,439

Earth 356,520 772,460 1,280,831

Thus, if the large estimate for Hogwarts is accurate and representative, then the calculations suggest that more than a million-and-a-quarter witches and wizards live in the world as a whole. The implications of this are even more profound, since it suggests a rather large space for large-scale wizarding interacts (such as the Quidditch World Cup). Given the efficiency of wizarding travel and communication, it would seem that a large, well-integrated, and complex wizarding world could be maintained by such a population.

Conclusion

This essay is by no means conclusive. As its author, I freely acknowledge that, while good at basic maths and statistics, I have had little formal instruction in statistics, which means that my mathematical algorithms are simple, perhaps even rudimentary. I am also not an expert on human populations, which compromises some of my assumptions. Finally, I'm not J.K. Rowling, so I don't know what caveats and so forth she might have in mind. I'm just a fan of the HP universe (especially HP/DM fanfics, I have to admit), wondered how many wizards there were, and put a little time into finding a reasonable answer.

Nonetheless, I think that this essay provides a workable analysis that allows for a basic guess as to the size of the wizarding world. It is thus hopefully of interest to those whose interest in Harry Potter runs to the esoteric, and it may also be useful in developing background plots. Thank you for reading this far. I hope that you have enjoyed it, or at least found it informative, and I would greatly appreciate any feedback or suggested tweaks to my methodology. For my part, I actually found it rather interesting to write, as the matter was rather more complex than I thought when first I considered the problem.

Cheers,

commendatore

Disclaimer - You may freely republish this essay anywhere you wish, but please have the courtesy to acknowledge its authorship, since this did require a bit of work to research and calculate. I don't own Harry Potter, and don't claim to, so please don't sue me.