This website is reader-supported. When you buy through links on our site, we may earn a small affiliate commission.

How Big Can Rats Get?

Last Updated: 16.04.24


When it comes to rats, people are divided into two categories. Some admit they are cute to some extent and think about adopting them as pets, while others only think of ways to get rid of them by putting a bucket rat trap out or using poisonous substances.

However, one thing is true – as much as we would like to blame these rodents for all the damage around our house or to our crops, rats can also be beneficial. So, if you think of bringing one at home as your pet or simply want to learn more about them, here is everything you should know.


How big can rats get?

There are many species of rats spread all over the world and their size and weight vary, depending on the breed and other local characteristics. The most common rat species you’ll stumble across are the Norway and the Roof Rats. An adult Roof rat usually weighs around 10 ounces and can easily get to 18 inches in length, including the tail.

The Norway rats are even bigger as they typically weigh 10 ounces or even more, and measure 20 inches in length, sometimes even more. However, the world of rats is no short of records and includes a 3-feet long rat from the Gambian Pouched species.

Other species like the Northern Luzon Cloud and the Bosavi Woolly rat both had individuals measuring more than 2.5 feet in length and weighing over 5 pounds.

Out of the world’s largest species of rats, the most common one you’ll find in the United States is the brown rat. However, specialists mention that there are a few invasive colonies of the Gambian Pouched that can be found in Florida.

There are other rats that don’t exceed a few inches in length and are mainly used as “lab rats” or pets.

In the wild, most of these rodents prefer living in colonies made up of 5 or more individuals. Most of them live at the ground level and can be easily found near gardens, ponds, trees, farms, trash or building foundations.

As for how many pups they can produce in a year, you should know that it also varies depending on the species. Generally speaking, a female rat can give birth to 5-8 cubs at once and can breed around 5 times a year. Some other species, like the Norway rats, mate even more often, up to 6 times a year, and can give birth to a dozen baby rats at once.

Their growth into adulthood

Rats are considered one of the strongest species of animals in the entire world, being able to withstand harsh weather conditions and backgrounds with scarce food supplies.

Throughout the centuries, they managed to develop and evolve in various areas of the world, especially because of their omnivorous food preferences. In other words, rats got used to eating leftovers from humans, apart from their regular foods, so that they adapted better and faster than other animals.

As a result, they no longer mate or breed in certain seasons, but they do it throughout the year. Thus, rats are able to rapidly expand their population and pose a real threat to crops or human health.

They also turn into adults in a relatively short period, after three-four months, meaning they are able to breed by that age. Therefore, even though most rats don’t make it over the age of one year in their natural habitats, their population can continue to grow, regardless of how low or high the temperatures in a certain area are.

If you want to prevent a future rat problem and dealing with numerous nests that affect your building and endanger your health, you should pay close attention to the structure of your house and its surroundings.

Never leave trash outside for more than one day, especially food leftovers. You should also seek to fix any water leaks and cracks in the walls where rats may build their nest. Moreover, store your food properly and, where possible, keep it above the ground.


Rats as pets

Obviously, rat pets are smaller species that don’t usually exceed a few inches in length and weigh about 2-3 ounces.

People have only looked into rats as potential pets in the past century, so they are not considered as popular as other animals like cats, dogs or birds.

1895 was the year when the first population of domestic albino rats was created in the United States and it was mainly for scientific studies. Over the years, specialists have noticed the similarities between the human body and that of rats, so they experimented on the animals first.

However, rats continue to be the least demanded rodent species for becoming house pets. Despite their affectionate characters and intelligence, they have a short lifespan of 1-3 years, which doesn’t make them suitable for households with small children. Moreover, they are very fast and can bite, so they need to be handled properly.

On the other side, rats can be easily trained if you have patience. They are loving and can learn new tricks with just a couple of hours of training per day. Rats also have a fantastic memory and are mainly used to test potential cures for all sorts of diseases and affections, including cancer and Alzheimer’s.

Rats and the spread of diseases

One of the main concerns regarding the population of rats is the animal’s ability to spread diseases. They serve as zoonotic vectors for the spread of various pathogens that lead to severe and deadly diseases, including leptospirosis and bubonic plague.

Although eradicated, the bubonic plague, which was responsible for the Black Death or the Great Plague, represented one of the most devastating pandemics in the entire world, with severe implications in Europe. It peaked in the old continent in the 14th century and was responsible for the death of more than 200 million people.

The Black Plague is believed to have traveled to Europe from Central Asia and killed up to 60% of Europe’s total population. The disease recurred as outbreaks until the 19th century and was spread due to precarious personal hygiene.

One common belief is that one of the deadliest diseases in the world was somehow connected to a Papal bull of Gregory IX, the ruler of the Catholic Church in the 13th century, and one of the most influential people at the time.

The “Vox in Roma”, issued somewhere between 1232 and 1234 caused a big fuss amongst Christians who were eager to get rid of heretics and everything that was considered “demonic” and black magic, including evil creatures like black cats. The following years are thought to have drastically diminished the population of cats throughout Europe, which led to the increasing number of rats, disease carrying-animals.

It is because of this uncontrolled rat breeding that Europe dealt with its biggest epidemics of the bubonic plague, killing millions of people. However, the story seems to leave aside various historical facts and stretches the importance of cats in killing rats, remaining a vague attempt to justify the spread of this deadly disease.

Nevertheless, rats continue to pose a threat to humans, as they are disease-carriers and crop pests.




Leave a comment

0 Comments Protection Status