Difference Between Mice and Rats

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The difference between a mouse and a rat.

Mice and rats have been under the scope of pest control agencies ever since there was such a thing as a “pest control agency”. We’ve developed a keen understanding of their behaviour, biology, and how to most efficiently get rid of them without doing any harm to the environment. First rule of the art of war is to know your enemy, and this is precisely what we do.

However, to the casual observer, it’s really hard to distinguish a mouse from a rat. If you want to learn the differences between mice and rats, this blog post will surely help you understand these rodents and set them apart.

Difference Between a Mouse and a Rat

The physical similarities between mice and rats is the reason so many people confuse them. However, once you’re aware of the differences, you’ll see they’re not as much alike as you thought. There are a few distinctive signs you can definitely tell if you’re looking at a mouse or a rat.



From a physical perspective, mice and rats have certain similarities, which makes it difficult to the uninitiated to set them apart. Some scientists believe mice and rats evolved from a common ancestor, but mice adapted to more comfortable habitats. By “more comfortable habitats” we mean your home. Hence, house mice are much smaller and a lot less menacing than their less evolved kin. A mouse has smaller heads and feet but sports a larger set of ears ( all of this relative to their size) than a rat would have. Their weight rarely exceeds 30 grams, the average being around 20. This difference is essential for mice control in order to determine the correct poison dosage to use.

When it comes to a size comparison, a mouse will be a lot smaller than a rat. A grown mouse is rarely longer than 20 cm (including the entire tail, which is usually as long as or longer than the body). The shape of their bodies is round and they’re covered in fur (except their tails, ears, and feet). Their heads are sharper than rats’ and smaller relative to their bodies.


RatsA rat is a lot more menacing than it’s rodent cousins. Rats have big heads with huge teeth they have to manage through gnawing. Since their front teeth grow rapidly, they have to gnaw a lot, which is one of the reason they’re so dangerous for a common household. Because of its hard teeth and incredibly powerful jaw muscles, a rat can chew through almost anything. Even steel pipes aren’t safe from a rat infestation, which means if you have rats it’s a good idea to take action and call an exterminator right away.

Rats are much bigger than mice. Their bodies can easily reach a length of over 30 cm, with tails exceeding 20 cm. Note just the length of the tail of a grown rat can easily be bigger than an entire grown mouse. Rats can weigh anywhere between 300 grams for females and 500 grams for males, on average.

Rats have bigger, more prolonged bodies covered with small, rough fur. Like mice, they lack hair around their feet, tails, and ears, which ensures excellent balance and navigation, making them only flawless acrobats, but also great swimmers, and talented climbers. So if you were thinking of killing a rat by flushing it down the toilet, think again. Not only will you probably fail, because they can hold their breath for around 15 minutes, but they can climb back up later (the chances of that happening are smaller than you winning the lottery, but it’s still not impossible).

Behavioural Differences Between a Rat and Mouse

Aside from the physical differences, there is also a number of behavioural differences that will help you differentiate between these rodents. These come especially in handy when you’re trying to deal with their pestilent presence in your home.


Mouse2Мice are crafty little vermin. They often build their nests near areas with readily available food sources, which is why your kitchen is usually the perfect place for mice to build their suburbs from paper and other soft materials (such as your favourite clothes, your children’s toys, or half your furniture).

Since they’re more used to living near humans, house mice are curious creatures. They will gladly investigate technical innovations in their environment (meaning they’re just as likely to get caught in one of our specialised traps as they are to chew through the cables of your new washing machine). Mice, like many other rodents are nocturnal. They’re a lot more active dusk till dawn, so you might hear them creeping around your house or chewing your wardrobe while you’re desperately trying to sleep.



Rats, on the other hand, are cautious creatures. They don’t get comfortable and rarely explore something new, which complicates an amateur’s attempts at rat control. During the course of their evolution, the rats that stayed away from new and unknown objects were the ones that managed to procreate the most, so traps can take a lot longer to work on a rat before they get used to it as a part of their environment.

A rat will rarely build a nest.
A more common practice for them is to use burrows or holes as their improvised home to provide shelter. If no suitable hole is available anywhere around, they are more than prepared to make one for themselves.

Because of their size, they don’t have a problem inhabiting larger territories, so their holes or burrows are not always close to their food sources. Since they’re also nocturnal, it’s far more likely to find a rat more active at night than during the day.

Rats and mice have a rocky relationship on account of the fact that rats usually kill mice. In fact, this is a well-documented behaviour. Because of their size and speed advantage, rats are excellent mouse hunters, who often eat their victims. Mice are aware of this and have evolved to avoid rats. This is the best way to protect themselves.  It’s the reason why rat odour is often a stressor for mice and deters them.

Procreational Differences Between Mice and Rats

In many ways, mice and rats are similar when it comes to procreation. Considering their common ancestry, this should come as no surprise. However, there are also some differences that have to be outlined.




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Мice are social creatures, which means if you see one in your home, it’s probably not alone. To make matters worse, they love to mate and they don’t care about incest, which means you can have a large number of mice in your house in no time. Mice gestation (pregnancy) period is around 19-20 days, and they only need 6 weeks to start mating. The average litter is around 8 babies, with female mice having 5 pairs of nipples.

Because of their smaller size, mice develop faster than rats. After birth, mice lactate for about 2 weeks. Pups are born naked and blind, but open their eyes 3 days after birth and are fully furred in 10 days.



Rat3Rats have a bit longer gestation period of 21-23 days. They are also unconcerned about incest, like mice, but take a bit longer to develop sexually and start reproducing around the 7th week, even though they’re often mature enough to do it earlier.
Female rats lactate for around 3 weeks and have 6 pairs of nipples. The average size of the litter is around 10. Like their smaller cousins, pups are born blind and naked. They open their eyes around the 6th day and they’re fully furred around the 15th. The slower development of rats is also related to their naturally longer lifespan. Rats are more cautious and have fewer predators than mice for that reason. Also, let’s not forget the facts rats are also one of mice’s predators.

How to Distinguish Mouse and Rat Droppings

When it comes to identifying what type of infestation you might have in your house, finding droppings is often times a good way to do it. Because it’s a lot more plausible to find the poo of an animal before you encounter it. Although it’s not a sure way to identify the pest you might have in your home.

Rat Droppings

Rat droppings differ depending on the type of rat you might have. Brown rats have droppings resembling a large grain of rice. Often times tapered at the end and in a cigar form.
Black rats have long and thin droppings with a slight curve. They are also smaller than the brown rat droppings.

Mouse Droppings

Mouse droppings are no longer than 8mm and are granular shaped. They also can be found all over the place. Often times the place where most droppings appear is very near the place where the nest is.


These are the most obvious differences between mice and rats. Mice are small, curious creatures who are still quite pestilent. Rats are much larger, heavier, more vicious, and even predatorial. Because of their behavioural and morphological differences, the approach to both can be quite different, but as experts, we’re well aware of the differences. And now you are, too. We hope our post was useful and interesting to you.

Please, share, comment, and let us know what you think. And if you have a mouse or a rat problem, we’re here to help.

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