During the early part of the series, it was assumed that humans were completely extinct, the only exception being Finn. That all changed with the revelation that Susan was a human, as well as the introduction of further human or post-human characters such as Moe, Martin, and Betty. By season 8, the known human population was about 6, give or take a few depending on whether or not you count the show’s various human-affiliated cyborgs, hybrids, and wizards.



Then came the Islands miniseries, where we are introduced to the survivors of the Great Mushroom War; a thriving community of humans living on Founders’ Island. But exactly how many humans are there on Founders’ Island? What is the total human population of Adventure Time’s world?

For all the following calculations, the final number we arrive at will need to be reduced by 62%, as this was the proportion of humans killed by Doctor Gross’ virus following Finn and Martin’s departure. This is assuming that not many humans have been born since then.



There are a couple of different ways we could approach this question. First of all, we can consider the ID numbers assigned to all humans born on the Islands. For example, Finn’s ID is PG87, and Susan’s is XJ77. These four digit codes seem to always consist of two letters followed by two numbers, meaning the maximum number of IDs is 26 x 26 x 10 x 10, coming to a total of 67,600. Accounting for Doctor Gross’ virus, this gives a final count of 25,688. So is this the maximum number of humans on the Islands? Possibly, but the ID numbers might be less restrictive than we have been led to believe, and it’s also possible that duplicate IDs can exist. Additionally, this number intuitively feels a bit too small for a dense city-state. So let’s try something else.

Referring to my calculation of the size of the Land of Ooo, Founders’ Island can be roughly approximated to a circle of radius 16 kilometres, giving an area of around 800 square kilometres. Aerial shots from the show make the island look a lot smaller, but I’ll write that off as artistic license. A size like this is also consistent with the canon Islands graphic novel, in which Jo takes many days to hike through the unexplored forests of Founders’ Island.

Now that we have an area, we can estimate a population density. The parts of Founders’ Island we see are a bustling metropolis, but presumably the whole island doesn’t look like that. So let’s find a real-life island with one large city: how about Barbados? Barbados has an average population density of 660 people per square kilometre, with around half its population living in the capital city of Bridgetown. Multiplying that by the area of Founders’ Island we get a population of 480,000, and reducing that by 62% due to Doctor Gross’ virus gives a final figure of 182,400. Quite a lot more than our first estimate, and a more comfortable figure for maintaining a sustainable population.

So in conclusion, the total number of humans who made it to Adventure Time’s present day is in the ballpark of 20,000 to 200,000. We can compare this figure to the Toba Catastrophe, an event which theoretically caused a huge reduction in humanity’s population around 70,000 years ago and is estimated to have left fewer than 20,000 surviving humans, from whom we are all descended. If we were able to recover from that, it seems totally reasonable that the number of humans on Founders’ Island is enough to sustain humanity in Adventure Time’s future.

Alternatively, we can get a little crazy. If we assume that Founders’ Island has the population density of Manhattan, 27,000 people per square kilometre, that gives a total population of 21.6 million, which becomes 8.2 million accounting for the virus; about the population of Switzerland, or London. But that feels like far too much.



As always, there is no true concrete answer. This is just a fun thought experiment and shouldn’t be taken seriously. I might do this for the Candy Kingdom at some point.

