Jesus Christ. My dad is a professor who works in sociology, and goes over census data all the time, and gets the same amount of info out. But holy fuck, you did this with only like 5 or so known facts. Kudos to you.

I found a table in the US census that says children age 10 to 14 make up 6.4% of the total population.
10,11,12,13,14 Thats 5 years so 6.4/51.28

11 year olds therefore just over 1% of the total population.

40 students in Harry's year gives an estimate of 4,000 as the population of wizarding Britain.

This is after 2 wars, Grindelwald and Voldemort so I'll put the "normal" population at about 16,000 at most.
More likely 6,000 to 8,000.

My actual calculation gave a result of 3,125. Which is so low inbreeding seems unescapable.

British wizards are doomed.

Id likes to add several things to this discussion you might find interesting.

1. The Texas Revolution. This Revolution likely caused a lot of trouble for American and Mexican wizards, considering both countries beat their opponents it is likely to assume the wizards at the time were at the top of their game. so war like this would of likely caused a magical neutral zone in Texas, be it a place where magic cannot exist or that the people are immune to magic. This would explain much of Texas history and why Texas is such an important state. It is the buffer zone between Mexican wizards and American ones. (Not to incite political controversy or anything.)

2. given how to spread out America is, it is also likely that either the government buildings are spread out, or several magical enclaves reside in the US. After all, Britain is a very compact country whereas the US is arguably Ginormous. True, apparition and portkeys may make travel easier but as has been seen in Harry Potter magical people aren't very nationalistic (except in quidditch, apparently...)

Does your calculations for the United States wizarding population take into account immigration during war like WW2/Grindelwald and the first Voldemort war? Also including possible wartime marriages, adoptions et cetera, and you might have a larger wizarding population for the U.S. and Canada.

A single note that certainly affects the calculations. By 1997 in just over 50 years magical Britain had been subjected to three wars against dark lords and given the length of time in these wars, we can safely judge that magical Britain is at a much lower population than it might otherwise be, with total possible losses equal to, at max, 3000-7000 wizards. Also, Wizards are generally shown to age slower, ie Dumbledore's 123 and Bathilda being significantly older than that, so figure generally death rates are lower. By 2010 the calculation might be closer to 1:5000.

Fascinating, and so helpful. Thank you.

This is pretty well thought out, and thanks for doing so. I'm going for the Native wizards were less effected by disease/conquest, so there's a much more indigenous influence on my version of American Wizarding. Glad to your analysis, and from other reviewers, I'm not alone in such a conclusion.

I agree with almost everything except MA should have a much higher population. It puts enormous value on education.
Plus it is very old and famously haunted.
Plus think of all the irish english settlers. Wizards would live there for the quality of education and for the history.

A very well thought out essay.

I found your article to be fascinating; you definitely made some interesting points, and the fact that you took the time to calculate all of this information out is pretty cool! I read an article one time where someone broke down the demographics of Harry's classmates and where they're all from in Britain, their socio-economic statuses and races, and how they represent very closely the larger scale of Britain's population. It was pretty interesting... I'd probably just start writing without thinking a thing about the numbers, but it's cool that other writers make the effort!

And to address the comment a couple people made about not seeing why wizards would have migrated to the US in the first place... are you kidding me? Witches were persecuted in Europe, remember? burned at stakes and stoned and all that... of course, those prejudices and persecution continued here *famously as we all know in Salem* but it's not as though those leaving Britain could have known that. (even though it's mentioned that real witches, like Wendelin the weird, couldn't actually be harmed by burning at the stake, one can still assume they had no desire to be discriminated against, if only on principal.) not to mention that i'm sure wizards and witches have desires to see the world just like muggles do- why should we assume all purebloods would just stay in England forever?

I once read a population estimate for Wizarding Britain writen by a geneticist. I forgot to bookmark the article and can't remember where I saw it, but it made some good points. The main point was that the class-size at Hogwarts probably represents a tiny birth-cohort. Harry Potters classmates, and their older siblings, are the kids conceived and born during the height of Voldemort's first terror-campaign. Based on this, the writer estimated that the adult population of Wizarding Britain was anywhere from 10000-20000, probably closer to 10000-15000, including not just wizards and witches but also 'Squibs' (Who we know have some sort of magical ability, because at least some of them can see spirits). I use the higher range for my own fanfic because it's the only way I can imagine Wizarding Britain having an isolated village, several encampments within Muggle towns, a commercial district/high street, several quidditch teams, two daily papers, a 'wireless'/radio network, a hospital, etc...

Anyway, this is a good essay. Very easy to follow. Thanks.

I found this really interesting. I've been thinking about the American Wizard population for a while. The thing I'm stuck on is how many pureblood families immigrated to America after its discovery. People originally moved her to make money, for adventure, or for freedoms they were denied elsewhere. It doesn’t seem like to many pureblood families would have a need to leave Wizarding Britain. What effect would this have on American Wizards? If they didn’t have Pureblood influence would they mingle more or less with local muggles? Would the half-blood population be significantly greater in America?

This is pure conjecture…sorry if I went into a rant there :)

Overall really liked your essay!

I follow your logic in this, however I have to disagree. I think from the many interview J.K has given that the wizardry population would be bigger than you estimate in America. As for attendance at the world cup, I think the number would have been really high, and not just for storytelling purposes, but because it IS the only game in town (as you say). Otherwise a very interesting take on things.

Thanks for the reviews, everyone. Just to clarify:

Taure: The 1:10,000 ratio I'm working with is simply a mathematical ratio. The wizarding population is about 1/10,000 the size of the Muggle population. I'm not making any assumptions about how many of those are pureblood, half-blood, muggle-born, or even squib. Sorry I wasn't clearer.

Shadowryder: The "city limits" of DC is only a small portion of the DC Metropolitan Statistical Area, which includes counties in Virginia, West Virginia, and Maryland as well as DC itself. The population of the entire MSA is nearly 10 times that of DC itself.

Wow, this is really detailed and well thought out.

The one thing that I'm confused about is Washington D.C. - in the overall population, you list it as having a magical population of only 60, yet you later list it as a top 20 wizarding population center with a magical population of 564.