How Big Can Rats Get? Over 3 Feet and 8 Pounds!

The ultimate size of a rat depends upon what type of rat it is and the available food supply. The largest rat that I have seen credible documentation on was a four-foot monster that weighed about 25 pounds.

The three most common types of rats are Woodrats, Norway and Roof Rats. While both of these rats can become quite large they are not the ones that can become 25-pound monsters.

Here is a quick video look at some of the biggest rats ever captured!
 <h2 class="lazy lazy-hidden wp-block-heading">Size of Roof Rats</h2> In general, an adult roof rat can weigh 5 to 10 ounces or more, their tail can reach more than 11 cm, and their body length can go from 13 to 18 inches or more. Pup Roof rats are born without hair and with shut eyes. At birth, they can weigh 4 to 6 grams per rat. Adult Roof rats are known to have shorter and smaller bodies with tails that are larger than their body size. Roof rats have a typical lifespan of one year which limits how big they can become. The ultimate size of a roof rat is also limited by its food supply.  Roof rats typically live in trees (including <a href="https://www.ratrelief.com/palm-rats/">palm rats</a>) or elevated structures where there is an adequate but rarely abundant food source. <h2 class="lazy lazy-hidden wp-block-heading">Size of Norway Rats</h2> A typical adult Norway rat can weigh 7 to 10 ounces or more, their tail can also be longer than 11 cm, and their body size can span a whopping 20 inches. Norway rat pups are born hairless and not fully developed. They have a birth weight of 5 to 6 grams each. Adult Norway rats have a very large and stocky body size with a tail that is smaller than their body. Norway rats have a typical lifespan of two years which gives them time to grow into rodents of significant size. Norway rats are burrowing, ground-based rats.  These are the rats that will infest trash dumps, grain storage facilities, sewers, and dumpsters.  Basically, areas where there is an abundance of food. The <a href="https://www.theguardian.com/environment/shortcuts/2018/nov/20/what-does-dorsets-21-inch-mega-rat-tell-us-about-food-and-the-modern-era">current record</a> for the largest Norway rat ever captured is almost two feet (21 inches) from the nose to the tip of its tail.  While that is certainly a massive rat there are other species that get much, much larger. <a href="https://www.huffingtonpost.com/entry/new-york-city-biggest-rat-matthew-combs_us_56e6c7a4e4b0b25c91826a94">Scientific studies have suggested</a> that the Norway rat has a physiological size limit of about two pounds. <h2 class="lazy lazy-hidden wp-block-heading">Size of Gambian Pouch Rats</h2> The Gambian Pouch Rat is a native of Africa and is typically noted as one of the largest rat species in the world.  These rats typically weigh about three pounds and have a length of three feet including their tails. These rats can live around seven years in captivity which gives them plenty of time to grow into monster rat size.  The long lifespan of these rats comes with another fascinating benefit; it makes it worth our time to train them! Trained Gambian Pouch Rats are actually superheroes!  People are using these rodents to detect live landmines in Africa so they can be defused before they hurt local villagers. <iframe data-lazy-type="iframe" data-src="https://www.youtube.com/embed/L0swUc492hU" width="560" height="315" frameborder="0" allowfullscreen="allowfullscreen">

Although these are African rats their population is spreading as people are importing them as pets. In typical fashion, these rodents will either escape or, once the owners realize that owning a monster rat is a bad idea, will be released.

There is currently a colony of Gambian Pouch Rats living in Florida whose population and progress are being closely monitored as an invasive species.

The four-foot, 25-pound monster rat mentioned earlier in this article was found on a playground in the UK. This is a controversial rat. Some people claim it was a Gambian Pouch rat that had been raised as a pet and then released into the wild. Some people doubt the size of the rat and suspect the picture was camera trickery.

Size of Giant Asian Rats

The true largest rats in the world are found on remote islands in Asia where they have evolved to giant size in the presence of plenty of food, warmth, and isolation.

Given the remote locations and difficulty of study an exact “world’s largest rat” has not been precisely determined. Here are some of the contenders for the title as described by the BBC and how they stack up against the Gambian Pouched Rat.

World’s Largest Rats

Gambian Pouched Rat: 3 feet long, 3 pounds
Northern Luzon Cloud Rat: 2.5 feet long, 5.7 pounds
Bosavi Woolly Rat: 2.7 feet long, 3.3 pounds
Sumatran Bamboo Rat: 1.6 feet long, 8.8 pounds

Other Frequently Asked Questions About Giant Rats

Do Rats Ever Stop Growing?

The good news is, adult rats do have a limit to how long they can get. However, if they have a steady and abundant food source, they will grow larger in weight, so it is safe to say that the rats’ environment have something to do with how much do rats weigh and grow. The really bad news is that a rat’s teeth don’t ever stop growing.

They counteract their rapid tooth growth by chewing on hard objects and food to wear them down. Without this constant chewing, rats’ teeth will overgrow and kill them from the inside out.

Do Rats Live in Groups?

Yes, rats, especially Norway rats, can live in colonies or groups of up to 5 or more rats. Norway rat colonies favor residing at the ground level where trees, bushes, flowers, gardens, ponds, orchards, near trash, farms, and below building foundations. You’ll find them digging holes deep into the ground. These holes lead to burrows or tunnels that vary in length, with chambers that also vary in size. These chambers house a mix of adult, young, and newborn or pup rats.

How Many Pups or Litters Can a Rat Produce?

Female adult Roof rats can give birth to 5 to 8 pup rats for every litter they have. They can birth up to 5 litters a year.

Female adult Norway rats can birth a litter of 6 to 12 pup Norway rats. They are able to have up to 6 litters a year.

How Can I Prevent Rats From Growing Out of Control?

You Can Remove Their Food Sources

Store your food, as well as pet food, in storage containers that won’t easily get bitten into. Cardboard and feed bags are easy for rats to chew through.

Clean Up Any messes

If your yard, garden, home, or business has things laying around, rats will love it. Rats will build a home out of materials that are found wherever they can get to. Norway rats love to make homes and burrow beneath piles of leaves, compost, garbage, and anything else. If you’re a business owner that has a stock of food supplies, put your food on a stack of pallets that are away from the floor.

Dry Up or Fix Water Leaks

If you have a leaky water hose, birdbath, or a leaky pipe beneath the house, rats will drink from it. If you or your child drink from the hose in hot weather, think twice before doing it again.

Keep Your Trees, Shrubs, Bushes, and Crops Maintained

Overgrowth will give rats a jumping board, home, and travel way to keep searching for food and supplies.

Close Off Access to Pipes and Trees

Purchase products that can be used to prevent rats from being able to reach and climb onto pipes and trees. These include metal tree trunk rat stoppers and pipe guards. Without intervention, rats will use these as a means of travel and escape.

Hire An Exterminator

There are professionals rat exterminators who know how to handle the species of rat you have and know which areas are susceptible to rat holes and tunnels. Experts like the Rat Relief Headquarters will do all the hard work for you, including killing filthy rats.

About Author

Noah Thompson

Noah Thompson is an expert in rat relief, providing invaluable tips and advice on effective rat control. With extensive knowledge in rodent behavior, he simplifies complex concepts, empowering readers to confidently tackle rat infestations. Through workshops and seminars, Noah equips communities with practical skills while advocating for humane treatment and control of rats.

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