Rats and Mice: How to Know the Difference (and Get Rid of Them for Good)

If you’re trying to name the worst possible house guests to have in your home, mice and rats are strong contenders. Each brings a certain ick factor when you find them in your home, thanks to the “gifts” (ahem, droppings) they leave behind, as well as the risks of disease they carry. When my husband and I were bright-eyed and bushy-tailed young adults and were looking to rent our first house, an immediate red flag should’ve been the musty smell we noted when we walked in. We thought, stupidly, “well, it just rained, and it’s probably musty smelling from that.”

A few weeks later we learned that there was, horrifyingly, a major rat infestation in that house. And getting rid of those rats took a lot of time and effort.

Don’t end up like us. Check out what these experts say is everything you need to know about rats versus mice in your home, what the differences are between them, ways to get rid of them and even prevent them from joining the family, and more. And hot tip: If you smell a musty odor, run away from that property or call an exterminator ASAP.

While mice are generally smaller than rats and have floppier ears and shorter and skinnier tails, “both rats and mice can cause damage to your home and carry numerous diseases, so proper rodent control is necessary if you notice either of these pests in your home,” says Frank Meek, board-certified entomologist and technical services manager with Orkin. “However, the method of removing these rodents must be tailored to the species.” 

Plus, a rat’s snout is “blunter” than a mouse’s snout, Meeks says.

According to Meek, mice are typically easier to trap than rats as they are more apt to explore new places. Rats are more cautious, taking longer to trap. They’re sneaky!

Their differences will also determine how you get rid of them from your home, says Jamie Nichols, senior service manager at Arrow Exterminators. “Rats are much bigger than mice. However, juvenile rats can often be mistaken for mice,” he says.

Unfortunately, both rats and mice can carry harmful diseases that pose a risk to humans, so it’s important to eliminate them if you see any signs.

Meeks says the three most common types of rats found in the home are the Norway Rat, the roof rat, and the cotton rat. 

According to Meek, there are a few things to know about each.

Norway rats are frequently called brown rats or sewer rats. They are large, bulky-looking rats that can grow to lengths of about 13 to 16 inches (yes, over a foot!).

The shaggy fur of Norway rats is usually brown or gray in color. Their ears and tails are covered in scales, and their tails are shorter than their head and body.

Roof rats are smaller than Norway rats. These rodents have long tails, large ears and eyes, and pointed noses. They have smooth fur with hairless, scaly tails that are longer than their heads and bodies.

Covered in long, coarse hair, cotton rats are known for looking like large puffballs. They are usually gray on their back with black hairs mixed in, and their undersides are light in color.

Often, cotton rats’ ears are almost hidden by their hair. From head to body, these rats range in length from 5 to 9 inches, with tails up to six inches long. 

Cotton rats are not common in all of the U.S. They’re typically found in the southern portions of the Midwest grasslands and parts of the Southeast.

Meek says the aptly named house mouse and the deer mouse are the types of mice typically found in homes.

“The house mouse is covered in short, light-brown or gray-black hair and is usually the smallest of these species,” Meeks says. They can grow up to 7 inches long from nose to tail, and you’ll notice that their droppings are rod-shaped and pointed on both ends.

As for the deer mouse, it’s small (up to 3 inches long) and multicolored, with a light brownish-reddish top and white underbelly and feet. These have a pointed nose and large, black beady eyes, and their ears are large with little fur covering them.

Meek says that around people, both mice and rats like to stay hidden as much as possible. That said, the mouse is more likely to “break cover” and dart out into the open than rats, he notes.

Nichols adds that sightings aren’t out of the question. “Depending on circumstances like population, available food sources, and construction of your home, it’s not rare to see either of them during daylight hours,” he says.

Both mice and rats are generally most active at night.

Meek says to look out for droppings and urine, gnawing evidence, foul odors (like the musty smell of my nightmares), nests, hidden burrows, and greasy rub marks. 

“Rodents have oily fur that leaves behind grease marks on surfaces they frequently touch,” Meek says. “Check for these marks along walls, baseboards and near doors or other entry points. Darker grease stains generally indicate their preferred routes.”

As for the odor, Nichols says, “Nesting sites will have a bad odor due to the regularity of them being there and the items used for nesting. Those nesting items could be insulation, paper towels, leaves, trash, etc.”

Of course, any droppings left behind will have a stink, too.

“The droppings for each will be similarly shaped, cylindrical and pointed at the ends, but they will have a major size difference,” Nichols says. Rat droppings can vary in size from 1/2 inch to 3/4 inch in length, and mouse droppings can vary in size from 1/8 inch to 1/4 inch in length. 

“Droppings are generally found in their travel paths and nesting sites, also along walls and mixed throughout insulation in the attic,” Nichols adds.

Both rats and mice are omnivores, “which means they will eat pretty much anything they come across,” Nichols says. While they enjoy seeds, grains, berries, and nuts, mostly any food will do (including dog and cat food, Nichols notes).

If you see signs of rodents, it’s time to act. While store-bought traps are available for DIY pest control, it’s usually not completely effective. Plus, unless you spot a rodent up close, it can be tricky to know what you’re dealing with.

Nichols recommends bringing in a pro, who will be able to identify the pest at work as well as create a treatment plan — not just setting traps, but also filling any holes and eliminating any openings where either mice or rats could sneak through.

“Just setting traps will not solve the problem. As a homeowner, make sure you do your part in eliminating food sources and harborage, in conjunction with a full exclusion. This is the best method,” Nichols says.

If you want to try to prevent rodents from entering your home in the first place, Nichols says it’s best to ensure your home is completely sealed everywhere — entry points, crawl spaces, basements, attics, and any other spots that could provide access.

“Anything short of this will not solve your problem in the long term. If rodents are already present in the home, then exclusion will be in combination with trapping,” Nichols says.

Meeks says to keep watch and be on the lookout for any activity listed above. He adds that you should sanitize by controlling your garbage, cleaning up after yourself, and keeping any food covered and out of sight — plus, share any rodent activity with your pest control provider ASAP.

Bottom line? If you have a rodent infestation, regardless of whether they’re mice or rats, you’ll need to take serious action. “Call a professional, have them inspect the home, make sure they offer a full exclusion with trapping and guarantee,” Nichols advises. Reputable companies will cover any additional visits they need to make within about a one-year timeframe of their initial treatment.