Rat vs Mouse: What’s The Difference?

Rat and mice share so many similarities it’s no surprise so many people mix them up.

However, understanding the differences between a rat and a mouse is actually pretty easy with the right information.

That’s why we decided to explore the most significant differences between rats and mice.

How Can You Tell a Mouse from a Rat?

Truth be told, mice and rats do have significant differences, such as size, head shape, and biological factors. However, for most people, both rats and mice appear extremely similar upon first glance. 

Considering most rodents don’t stick around long enough to take a selfie with you, you’re probably not getting a really good look to begin with. For this very reason, identifying rat vs mouse may be nearly impossible based on appearances alone.

And that’s ok because there are other indicators to help you positively I.D. which sort of rodent you’re home is being invaded by, rat, mouse, or both. Size and shape of droppings as well as any signs of damage (such as chewing and clawing) in your home, for example.

Some of the most significant difference in rat vs mouse:

  • Size differences
  • Head shapes
  • Length of tails
  • Significant biological differences
  • Size and shape of droppings

All things considered, rats and mice, despite similar appearances, are two individual species. Furthermore, a number of sub-species of both rats and mice exist as well. For the sake of this article, we’ll be referring to the most common types of rat and mouse; the brown rat and the house mouse.

Once we explore the differences between the two species, you’ll be able to clearly indicate one species from the other. Let’s have a closer look at the differences between rat vs mouse below.

Mouse vs. Rat – Size and Weight

The difference between size is one of the most significant between rats and mice, rats being the larger of the two. The body of a common mouse typically measures between 3 or 4 inches to as much as 7 or more inches. On the other hand, common rats range from 9 to 12 inches and can even grow to sizes exceeding 14 inches. 

In terms of weight, a mouse generally weighs a half to one ounce. Whereas, rats, the much larger of the two species, weigh many times more than mice (as much as a half and one pound)

Mouse vs. Rat – Color

Common mice and rats also share distinct differences in the colors of their coats. Mice typically range from grey and white to many shades of brown. They also have softer and fluffier fur than rats. 

In comparison to mice, rats tend to have longer and greasier coats. They are commonly grey, white, brown, black, and a variety of mixtures in color. Another difference in rat vs mouse is that rats may leave grease marks in areas they frequent. With mice, there are no such indicators of their presence.

Mouse vs. Rat – Heads and Tails

Right after size and color, the differences in head shapes between rats and mice is another significant indicator that helps to easily distinguish one species from the other. 

Mice have a small and triangular head shape with long floppy ears and protruding whiskers. Rats, due mainly to their size, tend to have a larger and fuller head shape with blunter noses in comparison to mice. The ears of rats may also be furless.

The length of the tail is another way to pinpoint the difference between a common rat and a house mouse. Rats have a much larger tail (surprise, surprise) than mice, measuring anywhere from 6 to 9 inches long when fully mature and completely lacking in hair. Mice tails are covered in hair and tend to mature at 3 to 4 inches long.

Biological Differences Between Mice & Rats

Besides the most visual differences in the appearance of rats and mice, there are some significant biological differences as well. 

One of the first biological differences is that mice develop at a more rapid rate than rats, opening their eyes approximately three days before rats. Mice also grow their first coat of fur around five days sooner than rats.

In terms of breeding, there are slight differences as well. Once a mouse reaches 50-days old, it’s mature enough to breed. That said, a female mouse can have as many as 10 pregnancies per year, giving birth to as many as more than a dozen baby mice each time. A female rat matures at merely 30 to 40 days old and carries pups approximately six times per year and births around a dozen babies at a time. 

A couple of more interesting and distinct differences in rat vs mouse are that rats have an extra pair of nipples (six pairs, in comparison to the 5 pairs mice have) and they actively hunt, kill, and eat mice (whereas, mice do not make a habit of killing or eating rats).

Mouse vs Rat – Shape and Size of Droppings

One of the easiest ways to distinguish rat vs mouse is in the shape and size of their droppings. Mice droppings tend to be extremely small (⅛-inch) and pointed at both ends, while rat droppings are curvy and measure well over half an inch long. 

All things considered, the shape and size of droppings is probably the surest way to determine whether a rodent is a mouse or a rat.

Difference Between Rat and Mouse Behavior

In addition to the physical differences between rats and mice, their behavior can also help to determine one from the other. For example, rats, which are larger and more aggressive, are also the more fearful of the two species. The instinctual fear that rats live with lead them to practice extremely cautious behavior and avoid exposing themselves for the sake of exploration.

Mice, though much smaller than rats, are the much bolder species. Curious about their surrounding environment, mice tend to boldly go where no rat has gone before, including straight to baited traps and their deaths. Rats, taking much longer to explore new territories, are definitely the harder of the two species to catch via traps.

Another pretty significant difference in behavior between rats and mice is that mice don’t seem to mind climbing. Rats, however, prefer sticking to lower domains such as crawlspaces and basements. Mice, ever the bold little pets they are, will end up on every level of your home including the attic.

Which One Causes More Damage, a Rat or a Mouse?

Generally speaking, rats and mice infestations can both cause a lot of damage. The sooner dealt with the better. That said, when it comes right down to it, rats may do more damage than mice. But, not for the mice’s lack of trying.

Mice gnaw into anything they can sink their little teeth into. Rats simply have larger and stronger teeth than mice, as well as being more powerful, which allows them to chew through much stronger material such as aluminum, cinder blocks, sheet metal, glass, and wood.

If you’ve got a mouse or rat problem, you can read our guides here on how to get rid of them:

Final Thoughts

Understanding the most significant differences in rat vs mouse can help you to determine which sort of rodent you’re dealing with. In turn, you’ll be able to act quickly, choose the proper pest-control option, and eliminate (or prevent) your rodent issue before it gets out of hand.

Jordan Quinn Farkas
Jordan Quinn Farkas
Jordan is a full-time writer from his home in Southeast Europe. An avid outdoors-man and backpacker, he has gathered a plethora of tips and tricks for dealing with all sorts of pests.

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