Do Mice Turn Into Rats?

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Written by Janet F. Murray

Published: September 18, 2022

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Mice and rats are rodents that people often confuse. But even though both these rodents live in the wild and sometimes in our homes, it is worthwhile learning to distinguish them. So, knowing the difference between mice and rats will be helpful, especially if you suspect a rodent infestation in your home, as these two rodents can pose different threats to your family. So, do mice turn into rats, and if so, what can you do if either invades your home?

House mouse

Do mice turn into rats? Rats and mice are two different species, so mice cannot turn into rats and rats cannot turn into mice.


Mice and Rats Are Two Different Species

Mice do not turn into rats. Although mice and rats share common features and are sometimes confused with being one or the other, they are two different kinds of animals. These two species are not even able to crossbreed. Both are rodents, but according to Bobby Corrigan, a rodentologist, comparing mice and rats is like comparing a house cat with a mountain lion.

Differentiating Between Mice and Rats

If you can take a close look at a mouse or rat, you will quickly be able to tell their differences. The primary distinguishing feature between these two species is their size. Mice are usually three to four inches long, with tails two to four inches long. Rats are much bigger, usually five to 10 inches long, with five to nine-inch long tails.

Mice fall into the small rodent category, while rats fit into the category of medium-sized rodents. Their tails are another good tell sign. Mice have thinner and smaller tails, while rats have thicker and longer tails. Finally, if you are uncertain whether you have rats or mice in your home, you can tell by their droppings. Due to their size, mice droppings are thinner and smaller than the longer and thicker rat droppings.

Could You Confuse a Baby Rat With an Adult Mouse?

Although you may think baby rats and adult mice may look similar, they are not. Even when they are babies, baby rats are still likely to be double the size of adult mice. Baby rats are also known to have oversized heads and hind feet which they grow into. This would be a strong tell sign as a mouse’s head and hind feet are proportionate to their bodies.

Identifying a Rat

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You can keep a rat as a pet or a pair of rats as pets but when wild rats build nests in your home, they become pests.

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Rat Characteristics

Rats come in a range of colors. Some are white, but most rats are neutral colors like browns, reds, greys, and blacks. These animals are usually five to 10 inches in size and have five to nine inches long tails. With most rats, their tails are longer than their bodies. Rats are also known to have relatively long ears and small beady eyes. Their eyes are often black or red, and their tails are long, thick, and usually hairless. They use their tails to assist them in grip when climbing. Rats have long noses, with some being blunt or pointed, but this depends on the species.

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Although rats and mice look a lot alike, adult rats are much bigger than mice and their tales are much thicker.


Burrows are Signs of Rats in the Home

If you know that rodents are in your home but have not physically seen them, there are signs you can observe to discern the species. For example, some rats create burrows in the ground or straw with entrances of two to three inches wide. These burrows are where rats sleep or store their food. Additionally, rats make holes in walls and flooring. These holes are often two to three inches in diameter but could be larger.

Look For Chew Marks

Typical signs of a rat presence in the home include gnaw and chew marks. Since rats’ teeth never stop growing, they bite and chew on things to maintain their length. For example, rats love chewing and gnawing on plywood, structural woodwork, plastic paneling, frozen ground, and even concrete in a home.

Nests Are Signs of Rats in the Home

You may also find a rat nest in your home. The nest may be at ground level or in an elevated space, like the roof, depending on the rat species. Rats build their nests with a range of materials. Commonly, rats make their nests out of wrapping from food remains, paper, straw, cardboard, rags, or shredded plastic bags.

Odors, Streaks, and Marks

You may also smell an odor or find streaks and marks on walls when rats live in or around your home. These marks are caused by using walls to guide their paths because their eyesight is poor. As they move along walls, they leave smudge marks from dirt on their bodies. Another significant tell sign would be finding droppings. Rats can produce up to 25,000 droppings per year, so you would likely find them in your home if rats are present. Rat droppings are distinctively blunt, black, and are 0.5 to 0.6 inches in size.

Identifying a Mouse


Mouse Colors and Physical Attributes

Mice also come in various colors but are often brown or grey with lighter-colored undersides. Mice are round, have pointed snouts, and have large ears. These rodents are three to four inches long and have tails that are two to four inches long.

Signs Include Chew and Gnawing Marks

If you know that rodents are in your home but have not physically seen them, these signs will help you identify them. Like rats, mice will also leave signs of gnawing and chewing on things around the house. These marks may be rough or smooth, and because mice use the same paths in a home, they leave tracks, smudge marks, and droppings.

Droppings, Urine, and Odors

And, like rats, mice leave a distinctive odor, indicating their presence. Their urine has a strong smell, which mice use to communicate with other mice. If you have an infestation, this smell may become overwhelming. Mice prefer eating seeds and cereals, so you will likely find chew marks and damaged items in your cupboards. Mice droppings are different from those of rats. The droppings are pointed and long while measuring 1/8-1/4 inches long.

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Mice are typically more delicate looking than robust rats.


Having mice in your home is a risk as their urine can cause allergies in children. Their feces also carry bacteria, and dust contaminated with feces can cause allergies or asthma flare-ups. If you notice any of these symptoms and think you might have a mice infestation, you should seek medical attention.

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About the Author

I'm a freelance writer with more than eight years of content creation experience. My content writing covers diverse genres, and I have a business degree. I am also the proud author of my memoir, My Sub-Lyme Life. This work details the effects of living with undiagnosed infections like rickettsia (like Lyme). By sharing this story, I wish to give others hope and courage in overcoming their life challenges. In my downtime, I value spending time with friends and family.

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