Calculating the exact net worth of the mouse from the Usborne "That's Not My…" book series
The first book in the series that has taken over my life.
As the parent of a toddler, I have spent a lot of time with Usborne Touchy-Feely books, specifically the That’s Not My… series by Fiona Watt with illustrations by Rachel Wells. The colourful pictures, simple text, and most importantly the tactile surfaces are all perfectly designed to capture the attention and imagination of the youngest readers. My daughter and I generally quite enjoy them.
No matter the overall subject of the book in question, each That’s Not My… book features one common element: a little white mouse who inspects each animal or object. The mouse inevitably dismisses a handful of alternatives before declaring, “That’s my _____!” on the final pages. It’s a simple and strict formula clearly intended to help babies and toddlers with pattern recognition.
But after going through such varied books as That’s Not My Monkey, That’s Not My Dinosaur, and even That’s Not My Santa, I began to wonder: if this little white mouse actually owned all of these things, would its minimum net worth be tied for 908th place on the Forbes Billionaire List as of March 1, 2026?
The answer to that extremely specific question is yes. The more interesting thing is exactly how the Usborne mouse ended up with a fortune comparable to that of a German drugstore magnate or the cofounder of Mailchimp. (The exact value is listed at the end of this post, along with a link to my complete spreadsheet.)
Ground Rules
Firstly, I have recognized 86 distinct books in this series, including 83 traditional Touchy-Feely books and 3 jigsaw books that follow the same basic formula and still feature the mouse. I have excluded books that are simply rereleases of existing books (e.g. with an included toy or a smaller format with a ribbon to tie onto a stroller). The one exception is That’s Not My Princess, which has two versions with distinct content; as a result, I have assumed that the mouse has two different princesses. (Oh no, we’re already talking about owning humans.) I have also excluded the activity books because I forgot they existed until it was way too late to bother with them.
Secondly, this guide will use American dollar values for everything. While I am not American myself (insert patriotic maple leaf here), many of the animals owned by this mouse are illegal to own or breed in much of the world but legal in several US states. Furthermore, the sheer size and breadth of American capitalism give me an incredible wealth of information about putting exact prices on utterly random things.
Thirdly, in most cases, I have tried to place the “value” of a thing at the low end of its average range. This is by no means an exact science, but my goal was to calculate a realistic lower bound for the mouse’s fortune. We can then assume that the mouse’s actual net worth is somewhat higher than my lowball estimate.
Lastly, the mouse is not bound by human laws. Mice around the world commit breaking and entering, food theft and tampering, and tax fraud on a daily basis. Despite this, the number of mice arrested and charged for their crimes stays stubbornly at zero in every country. The Usborne mouse knows this fact and abuses it. Although the mouse will follow the law whenever it is convenient (why go to the trouble over a frog that you can just “add to cart”?), endangered species regulations and other laws that prevent the mouse from “catching ‘em all” will be ignored. For example, thanks to That’s Not My Robin, we know the mouse owns a robin despite laws existing in most countries against owning migratory birds. These laws don’t even make exceptions for billionaire vigilantes wanting to adopt robins orphaned in horrific circus-related accidents, let alone cartoon mice, so we must necessarily flaunt them.
Not all robins are migratory. This one is clearly staying for the winter. Just let me buy a robin!
Easily Priced: Commercially-Available Objects and Animals
Much to my delight, a large number of the mouse’s possessions are readily bought and sold on the open market, meaning we can assign very reasonable dollar values to each of them.
The first, and easiest, category to price was everyday objects. In this category, the mouse owns a doll, a snowman, a teddy bear, a Christmas tree, a pumpkin, and an Easter egg. I have also added the robot to this category because the art style of the book suggests it is an electronic toy rather than a state-of-the-art automaton. In most of these cases, I just came up with reasonable estimates off the top of my head, with the exception of the robot and the Christmas tree, for which I used online store listings. The total value of this category was $334.99.
Next, the domesticated animals category includes both household pets (from dogs and cats to somewhat rarer options like hedgehogs and axolotls) and farm animals. With a few notable exceptions like the cow and the parrot, each animal in this category was not outrageously expensive. However, with 22 different animals represented, the value quickly added up to a total of $7,113.73.
Lastly, the “exotic” animal category included all wild animals for which I could find typical prices from a breeder. This was the most surprising category. Like, did you know you can legally own a sloth in several states? I sure didn’t, and I’m not sure how I feel about that. Even more surprisingly, they aren’t even usually that expensive, all things considered. It is very possible to get a kangaroo, a lemur, or even a small shark for less than some purebred dogs. Even within this category, a regular gray squirrel ($1,199) is somehow more expensive than a meerkat ($950). I am not an exotic animal economist, so I cannot explain any of this.
Nothing else in this category, however, approaches the figurative and literal heights of the most expensive animal so far: a giraffe. You can apparently buy American-bred giraffes online, but it will set you back at least $90,000 for a male, with females being even more expensive. The eye-watering price tag of the giraffe alone accounts for over 70% of this category’s total of $125,999.98, despite 11 other species being included.
Sidebar: That’s Not My Farm
Two books feature the mouse owning real property as opposed to mere chattels. The first, That’s Not My Farm, is relatively straightforward to price out. The picture in the book includes a cow, a pig, a sheep, a hen, and a tractor. If we count That’s Not My Lamb and That’s Not My Chick for the sheep and the hen respectively, all of these animals are already accounted for in the previous section, and That’s Not My Tractor will be dealt with later.
Therefore, we are free to just consider the cost of the land. Even in this economy, the median price for a small farm in the United States is currently $549,000. If only the second book involving real property was so easy to figure out…
Not Even Jeff Bezos Is Allowed to Own These: The Illegal Animals
18 animals in the series are fully illegal to own without a special exemption for a licensed zoo or wildlife sanctuary (more on that later). Some of these are obvious, like elephants, bears, and hippos. Others are less obvious; many common birds, like owls and robins, are banned from private ownership due to animal welfare concerns. However, as previously noted, the Usborne mouse spits in the face of the Convention on International Trade in Endangered Species of Wild Fauna and Flora.
Now, the funny thing about the black market is that, for some reason, it’s hard to find specific prices or providers for illegally sold animals. I’m sure I could have done more research to get better numbers, but I’m pretty sure I’m already on a watchlist for my Google searches for this section. I don’t think the police would accept “Reddit creative writing project” as a legitimate reason to contact Singaporean badger smugglers on the dark web.
The prices were all over the place in this category. I found an article talking about otters being sold for $40 on Facebook in Indonesia. I found a classified ad for a seller in Florida (where else?) claiming to offer an entire colony of 20 Egyptian fruit bats with a habitat included for $4,500. If you know the right people, you can apparently procure an owl in India for $210 for the express purpose of animal sacrifice.
Of particular note here is That’s Not My Monkey. The so-called monkey over which the mouse claims ownership is not even a monkey at all; it’s an orangutan. This fact has persistently irritated my wife and me. (You can get an orangutan on the Thai black market for $9,000 according to wildlife activists.)
But even the deepest depths of the first page and a half of Google results have limits to their depravity. There were several animals I could not properly price from historic sales, inexplicable classified ads, or news reporting. Therefore, I had to get creative. For the penguin and the wombat, I had to settle for taxidermy. For the whale from That’s Not My… Under the Sea, I had to settle for a skeleton being prepared for display in a museum. For the narwhal, I had to settle for just the horn. For the polar bear, I had to settle for a study commissioned by the Canadian government calculating the precise economic value of each living polar bear in the world. (Yes, this was a real study. Each bear is worth almost $288,000, for the record.)
There was only one animal I could not price at all without resorting to a different species: the European robin. Yes, of all the animal-based books, That’s Not My Robin almost became my villain origin story. After result after result reminding me of how illegal it is to own migratory birds, I settled for the price of a linnet finch, which kinda looks similar if you wear glasses with an incorrect prescription. So much work for only $250 added to the total.
The undisputed king of this category was the panda. Fun fact: virtually every panda in the world is directly owned by the government of the People’s Republic of China. China lends them out to zoos around the world, but retains ownership of them and any offspring. Zoos love them because they often massively boost visitor numbers; China knows this and charges a leasing fee of around one million dollars per year, per panda. Not even the Usborne mouse wants to risk smuggling a panda out of China illegally, so we are ponying up a cool million for the one-year lease and calling it close enough.
With the panda making it rain renminbi, the grand total for the illegal animals category comes to $1,922,851.00.
The Elephant (and Other Assorted Animals) in the Room: That’s Not My Zoo
At this point, we could simply add the animals together and get a grand total of $2,055,714.71 for all of them. But surely the mouse must have somewhere other than its little hobby farm in Minnesota to keep them all, right? Well, this is where we come to That’s Not My Zoo.
The only animal sound I'm making is \"Aaaaaarghhhhhh\".
Putting a dollar value on a zoo is tricky because there are so many variables involved. While the picture in the book only includes an elephant, tiger, parrot, and monkey, we can reasonably assume this one picture does not depict the entire facility. Furthermore, most modern zoos get their animals through a mix of breeding, inter-zoo transfers and exchanges, and rescue animals, and obviously get special exemptions from laws against ownership of exotic or wild animals. If we assume the Usborne mouse got its animals this way, then all my research into the black market and my resulting profile in an Interpol filing cabinet were for nothing.
At the low end, we can expect the value to be at least around $3 million. In 2022, the Greenview Aviaries Park & Zoo in Ontario was listed for sale for CA$4.5 million, including all the animals contained therein. While this zoo contains a number of high-profile species like lions, zebras, ostriches, flamingos, and capybaras, it is too small to accommodate large herbivores like elephants, hippos, and giraffes. Still, it gives us a reasonable estimate for what a small zoo might cost.
At the opposite end of the privately-owned zoo spectrum is the Phoenix Zoo, which is owned and operated by the non-profit Arizona Center for Nature Conservation. According to their 2024 financial statements, the total net assets (including property) of the organization were valued at $99,173,131. This zoo is equipped for large herbivores, and specifically had an elephant exhibit until 2025, when its last one died. However, there are still some species in the mouse’s menagerie that even the Phoenix Zoo could not reasonably accommodate, like the shark and especially the dinosaurs (more on those later).
Therefore, if the mouse simply bought a zoo in order to acquire most or all of its exotic animals, it is reasonable to estimate that it would have had to spend at least $100 million. However, that would zero out most of the animal acquisition costs above, with the notable exception of the $1 million panda lease.
Alternatively, the mouse could have acquired a “starter zoo” in the low six figures and built up its holdings through more questionable means. In this scenario, the total price tag would be “only” $5,291,714.71, including the panda lease. A real bargain if you don’t mind international warrants for your arrest, which we know the mouse does not. Ultimately, the more likely scenario is up to you to decide.
That’s Not My Zoo has one interesting final wrinkle in the form of the animals depicted. As with the farm, we can assume the elephant, tiger, and parrot are the same animals that the mouse owns in other books. However, this book is the only one that shows the mouse owning a true monkey (recall That’s Not My Monkey featured an orangutan). Since we are this deep in already, I am going to assume that the monkey came free with the zoo. I will accept no further questions on this matter.
We’re Back: A Dinosaur Story
I told you we’d come back to the dinosaurs. The series features two dinosaur-themed books, That’s Not My Dinosaur and That’s Not My T. Rex. In the first, the mouse is revealed to own a live Stegosaurus; in the second, it gets ownership of… well, you read the title.
Now, in our world, the dollar value of a live dinosaur would be incalculable. But the mouse does not inhabit our world. The mouse lives in a world where there are not only multiple living dinosaurs, but so many that the mouse actively forgets which dinosaurs belong to it.
Thankfully, we have a precedent for such a world. A world where living dinosaurs have become so boring that they have to start inventing new ones. A world where people see a dinosaur on their morning commute and think, “Dang it, with this traffic, I won’t have time to stop for coffee anymore.” A Jurassic World… world.
Jurassic World Evolution is a management simulation game in which the player essentially constructs their own version of Jurassic Park. Part of running this park is buying dinosaurs to put on display, meaning the game features a complete price list for all the species in it, including Stegosaurus and Tyrannosaurus. Furthermore, these prices are roughly in the ballpark of the prices from the auction scene in Jurassic World: Fallen Kingdom, so I’m just going with it.
Using the values from Evolution, the Stegosaurus is worth a little over $403,000 and the Tyrannosaurus is worth almost $2.9 million. In total, the two dinosaurs alone account for $3,288,868.00, enough to lease 3.29 pandas for one year.
Humans and Humanoid Beings
Oh boy. Accounting for That’s Not My Pirate and both distinct versions of That’s Not My Princess, the mouse supposedly owns three humans. Seven other books involve ownership of humanoid and presumably sentient supernatural beings, from an elf and a mermaid to a literal angel and Santa Claus himself. After all my research into animal smuggling, I am not adding human trafficking to my search history, let alone whatever sort of occult magic I would need to use to capture a Christmas fairy.
In this instance, and this instance only, I am going to use the most powerful weapon in the English language: lexical ambiguity. When I say I am going to see “my” doctor, I am not implying that I legally own her. “My” lawyer does not live in a cage in my basement. But most importantly, the owner of a small business might very reasonably make reference in conversation to “my employees” without engaging in chattel slavery.
Interpreting the word “my” in this way solves two problems. Firstly, we have no need to do a deep dive into the horrifying world of modern slavery in a silly Reddit post. But secondly, it provides us a way around the fact that elves, mermaids, and fairies do not actually exist. After all, there are a few different places on Earth where you can readily find princesses, stereotypical swashbuckling pirates, and witches and put a dollar value on their time: Disney theme parks.
Almost all of the humans and humanoids in this category are therefore being interpreted as Disney cast members, the costumed actors who portray characters and pose for photos with guests. According to the most recent collective agreement negotiated with cast members at Walt Disney World in Florida, the minimum wage of a cast member is set to rise to $20 per hour by this fall. Let’s assume that in order for the mouse to call each cast member “my” princess/mermaid (or all of the above if it’s Ariel), they must be employed full-time at 40 hours per week for 50 weeks per year. That math results in an annual salary for each cast member of $40,000. I am also giving this salary to the angel because I assume she would walk off the job if she got paid less than the others. I will finally also throw in That’s Not My Monster and assume said monster is equivalent to a cast member wearing a mascot suit from Monsters, Inc.
The exceptions to this calculation are the expressly Christmas-themed characters. Outside of some very specific exceptions like Santa’s Village in Bracebridge, Ontario, no one expects or particularly wants to see Santa Claus in August. Therefore, Santa, the elf, and the Christmas fairy are only seasonal employees hired for the six weeks leading up to Christmas. The supporting characters will share the $20 per hour wage of the Disney cast members, but Santa himself will get bumped up to $30 to reflect the median earnings of a mall Santa in the United States.
In total, the annual salary of our 11 human actors comes to $336,800.00, or barely one-third of a panda. (No, I’m still not over this.)
Other Fantasy Creatures
Back to ownership, just as Adam Smith intended.
The mouse has two non-humanoid fantasy creatures, namely a dragon and a unicorn. Obviously, neither of these animals actually exist, but they seem real enough in the mouse’s world. And unlike our living dinosaurs above, we do not have a convenient lookup table for their hypothetical dollar values.
Once again, I had to get creative. For the dragon, I was able to find a website offering reasonably lifelike animatronics for surprisingly affordable prices. For just $2,600, you too could have your own theme park-quality dragon to frighten away home intruders.
Meanwhile, for the unicorn, I found a listing for a white, hypoallergenic “fantasy horse” that seemed close enough for $5,900. Throw in an extra $100 to stick a horn on its head, and congratulations, you now have a unicorn!
This means our two remaining fantasy creatures contribute another $8,600.00.
Planes, Trains, Automobiles, and Time Itself
Nine of the 10 remaining books feature various vehicles. In order to narrow down price estimates, I have looked for specific models that are visually similar to the ones in each book. For example, the car in That’s Not My Car has a boxy frame and rear-mounted spare tire that make it a dead ringer for a Jeep Wrangler. The bus in That’s Not My Bus is a London-style double-decker bus. The digger in That’s Not My Digger is a backhoe loader that I managed to somehow find for sale on Amazon of all places.
In most cases, this research was the most straightforward I had done since the domesticated animals. The most difficult vehicle to value was the train in That’s Not My Train, because it was an old-fashioned tank locomotive that has not been in production for decades. However, I found a train enthusiast forum that suggested such a locomotive in good working order would be worth around £45,000, and I absolutely trust train enthusiasts to know their stuff.
And now we have truly reached the big leagues. That’s Not My Plane reveals the mouse to own a fully flight-capable four-engine jumbo jet. Prior to the model ceasing production in 2023, the Boeing 747-8 was listed for sale at a staggering $400 million per aircraft. Just this plane alone eclipses the value of every other item on this list combined, enough to lease 400 pandas for one year or one panda for 400 years. Surely there cannot be anything more valuable than that, right?
Enter That’s Not My Halloween.
That’s right, the mouse owns the concept of Halloween. The National Retail Federation estimated Halloween spending in 2025 at $13.1 billion in the United States. However, we cannot in good faith just add that money to the mouse’s total. Instead, we can reasonably assume that the mouse simply collects a royalty of sorts for allowing Halloween to continue to exist. As a representative example, the Sicilian Mafia often expects companies under their “protection“ to pay a minimum of two percent of their revenue as pizzo. Assuming the mouse charges a similar two-percent rate to the full value of Halloween, the mouse ends up with a massive… $262 million. Less than the plane. Huh. That’s anticlimactic.
But wait. There is one more book left.
That’s Not My Rocket ends with the mouse in a capsule with two large booster rockets still attached and the Moon looming large in the background. The implication is clear: the mouse is headed to the Moon. And conveniently, we as a species just went to the Moon for the first time since 1972, so NASA’s Artemis II mission is the perfect comparator.
I will let DW News do the talking for a moment:
>Building and launching a single Orion crew capsule costs around $1 billion, according to a report by NASA's inspector general published in November 2021.
>Add to that $300 million for the "service module" that provides power and life support, which was supplied by the European Space Agency.
>The launch vehicle, including its rocket boosters — called the Space Launch System — costs around $2.2 billion, and finally there is another $570 million for the necessary ground infrastructure, including mobile launchers.
>That means each flight of Artemis I through IV costs around $4.1 billion.
That’s it. That’s Not My Rocket singlehandedly launches (pun intended) the Usborne mouse from a mere multimillionaire to a multibillionaire on par with the former owner of the Washington Commanders. Nothing else comes close. Not even the panda.
Conclusion and Citations
The Usborne mouse is undoubtedly among the richest characters in children’s fiction. Even if you discounted the rocket and assumed the mouse just paid to hop onto a Virgin Galactic flight, its net worth would still exceed the GDP of at least six sovereign countries. But its exact fortune depends on your choices about how it acquired all of its animals.
At the low end, if you assume the mouse bought a small zoo and filled it with animals bought individually through a variety of legal, questionably legal, and definitely illegal means, its total fortune is $4,774,232,304.88.
On the other hand, if you assume it just bought a functional zoo already full of animals and followed standard ethical procedures for acquiring its animals, the estimate rises to $4,870,496,177.92. This number assumes that common pets (e.g. cats and dogs) and farm animals (e.g. cows, pigs, and chickens) were bought separately for the mouse’s hobby farm, and that it still had to pay extra for the whale and the panda lease.
If anyone wants to see the full breakdown, I have a spreadsheet here with the exact value for each item and the source I used to find it.
Join me next time when I apply Jungian psychology to the Pop-Up Peekaboo series or something like that.