How Much Does a Bat Weigh?

Calculating weight is always a tricky concept, and that’s especially true for bats. For one thing, for as tiny as they can be, bats come in all sizes, big and small, slim and not so slim. Megabats and microbats are wildly different in size, in part because they have quite different diets, so the idea of an “average size” for bats is as ludicrous as claiming an NFL linebacker and ballerina should be compared on the same scale.

What’s more, nobody wants to body shame bats, but the fact is that calculating their weight can be a bit tricky given the fact that it can fluctuate wildly, depending on when they’ve last eaten and how they’re carrying it. In fairness, we’re all a little full after dinner, and while we chow down on holiday dinners and excuse our expanded waistlines afterward, we don’t have the same excuse bats do – that they’re building up necessary fat reserves for winter hibernation.

That being said, we can still measure the sizes of different bats and see who tips the scales as the heftiest and the most petite.

Megabats vs. Microbats

The formal name for that aforementioned difference between larger and smaller bats is “megabats and microbats,” with the former being typically omnivorous or else eating fruit entirely and the latter being more inclined to suck blood and eat insects. That doesn’t mean that these little guys are any less ravenous, however, as little brown bats can eat half their body weight every night. That’s because it takes a lot of energy to fly, and bats have an incredibly fast metabolism, meaning they burn calories fast, which they then slow down in order to hibernate.

The Biggest Megabats

The bat that tips the scales as the biggest in the world is the golden-crowned flying fox. There are several flying fox megabats, and they tend to live throughout Asia, Africa, and Australia. However, the golden-crowned flying fox is native and exclusive to the Philippines. The wingspans of these immense bats can stretch to five and a half feet, and they can tip the scales anywhere from 2.6 to 3 pounds. It is worth noting that the bats’ wingspan is far larger than their actual height, which is typically between seven inches to just short of one foot. Like the little brown bat and other bats, this species also eats a significant portion of its body weight per day to keep up the energy reserves it needs to zoom through the sky with its enormous wings. They are also arguably the smartest bats in the world, with an intelligence level comparable to that of some dogs, and they are even capable of learning tricks.

Like so many bats around the world, golden-crowned flying fox bats are sadly endangered, primarily due to human encroachment on their environment.

The aptly-named golden-crowned flying fox bat certainly does deserve its crown as the largest bat in the world, but there are plenty of others which have a fair amount of heft as well. Flying fox-type bats are one of the most common types of bats to appear on lists of the largest bats in the world.

Another flying fox-type bat, the Comoro flying fox, also known as Livingstone’s Fruit Bat, is notable not just for its heft (1.75 pounds) but its brilliant coloration along its guard hairs, which are golden and look resplendent against its black body. Unfortunately, this species is also being threatened by the loss of its habitat due to deforestation and other acts of human intervention.

The Sulawesi flying fox is just a few ounces lighter on average, hails from Indonesia, and features remarkable golden brown coloring. It feeds mostly on coconuts and breadfruits. These huge bats aren’t huge on the spotlight, however, and tend to prefer to keep to themselves in large colonies, lashing out at intruding humans. That said, they are still integral to the Indonesian ecosystem, as they do a lot of pollinating.

Yet another flying fox-type bat, the insular flying fox, is thankfully far more abundant and less threatened in its Pacific Islands home than the other flying foxes mentioned above. It sports an elegant yellow “ruff” of fur around its neck and black body fur. What’s more, while males tend to be larger than females in this species, the sexual dimorphism is lesser in this species than in other flying fox-type bats. They can be found populating lowland forests and areas with a similar ecological makeup, although they can also be found in areas wildly different from that, such as steep mountains and cliffsides, rainforests, swamps, and wetlands. They weigh an average of 1.3 pounds, which is especially impressive given that they achieve that weight by eating pollen and nectar.

The Mariana fruit bat (still a flying fox-type bat despite its name) weighs in around 1 pound even, and combines a golden “ruff” of neck fur with black or brown body fur. It is primarily found on the Mariana Islands, and its forearm can be as large as 15 centimeters, but unfortunately, this bat is also considered a delicacy and so has been hunted to the point of being endangered.

Finally, there are straw-colored fruit bats, which are found in North Africa and the Middle East. They weigh less than 1 pound on average, usually around 12 ounces, but that’s still “big” compared to some bats, and they also lay claim to one of the biggest migration paths of any mammalian species. These brown and tawny bats also have a very large social circle, living in communities of as many as 1 million bats.

The Smallest Microbats

When it comes to microbats, the “biggest” of these small bats is the false vampire bat. This Nos-faux-ratu weighs 5 to 6 ounces and features a wingspan of 40 inches. If that sounds pretty small, compare it to the bumblebee bat. Also known as Kitti’s hog-nosed bat, it’s not just the world’s smallest bat, but the world’s smallest mammal, measuring around 1.3 inches long and weighing a scant 2 grams – roughly as light as a penny. They roost in groups of no more than twenty and feast on insects and spiders inside caves. Found primarily in Thailand, they are legally protected, but still face habitat issues due to human activity.

By comparison, the dwarf epauletted fruit bat may seem gigantic, measuring around 3.5 inches long. Likewise, the white Honduran bat is a few centimeters long and tips the scales at a petite 5 to 6 grams. And if it were not small enough, it is also one of the only bat species in the world that does not have a tail. While they are called “white” Honduran bats, they can appear green when the light hits them from the right angle while they are perched on leaves. This helps to camouflage them.

As we can see from this list, there is a lot of variation when it comes to the size of bats. The flying fox megabats are easily the biggest, typically weighing a few pounds, while bats such as the bumblebee bat and white Honduran bar are incredibly small—just a couple grams each. Still, even the heaviest of these bats are far from what we would call heavy. Whether they’re as big as a massive bird or tiny as a hummingbird, bats come in all shapes, sizes, and weights.