Rat Lifespan and Life Cycle

Home » How to Get Rid of Rats » Rats » Rat Lifespan and Life Cycle

“Know your enemy” is a proverb that is true in much more than just war as it carries invaluable wisdom in our work, our day-to-day lives, as well as dealing with rat infestations. Knowing how long do rats live, what’s the rat gestation period, how many rats in a litter can be expected, as well as all the other minor and major details about the rat reproduction and rat life cycle, can greatly increase your odds of finding the best solution and dealing with the rat problem using rat traps or rat poisons .

Rats are well-known for a lot of things, including the short rat lifespan. Rats live fast and die after a short while, but that doesn’t prevent them from reproducing like crazy and quickly overrunning any dwelling they settle in if they don’t face resistance. The key to the exponential growth of any rat colony is their birth rate.

Rats birthing and litters

Depending on their exact species, rats tend to birth around 4 – 6 litters per year (one litter every 2 – 3 months) with each litter averaging 6 – 12 rat babies. In other words, the answer to the “How many babies do rats have?” question is “An awful lot.” If even a single “rat couple” sets shop in your crawlspace or basement and is left unchecked, you can expect up to 70 new rats on your property after one year, and that’s not counting the rats that these initial first rat generations will produce themselves. And in case you were wondering – male rats reach maturity after 60 – 80 days, while female rats typically reach maturity after about 90 days (with small variations depending on the species), so after just 3 months you’ll have several more rat couples that will join the reproduction process.

Add to all that the fact that rats are social animals and you’re much more likely to face a group of rats rather than just “a couple” and you can see how a rat infestation can grow out of control in just a couple months. It also becomes quite obvious why it’s vital to locate the rats’ nest and not just kill or capture the adult rats that are walking around your property. For every adult rat, you capture or kill there are significant baby rat numbers growing back in the nest.

Rat lifespan

Of course, the rats’ quick reproduction cycle has its checks and balances, namely their short lifespan. Depending on their exact species, wild rats tend to live for just 2 – 3 years, which is still significantly longer than wild mice, which rarely live more than 10 – 12 months. In captivity, rats can sometimes live up to 4 years if they are taken proper of and there are some unverified reports of rats reaching the astonishing age of 5 years.

The main cause of death observed in laboratory rats is cancer, with different strains found in different species. A lot of older rats also tend to form various degenerative conditions such as multiple kidney failure diseases. These all tend to form only in the latter stages of a laboratory rat’s life cycle, however, and up until then, laboratory rats are mostly healthy and sturdy animals.

Generally speaking, the rat pests that are likely to invade your property won’t live longer than a couple of years because of the various diseases, predators, and harsh conditions they are forced to suffer (as well as our own efforts to exterminate them and drive them off our properties).

Related Pieces

Other rat life cycle time traits

As we said, depending on their exact species, wild rats can live up to 2 – 3 years and reach reproductive maturity after about 3 months. They also tend to produce new litters once every 2- 3 months which means that the average female rate will produce 8 – 12 litters throughout her life. Each litter can vary between 6 and 12 baby rats so that’s means that the average female rat can have anywhere between 50 and 150 children in her life.

The gestation period of the average female rat is about 21 days (depending on the species), so that’s 3 weeks of pregnancy for every 5 – 10 weeks of non-pregnancy in a standard female rat’s reproductive cycle. Rat babies typically go through about 21 – 28 days of weaning until they start sucking milk completely and start needing other food. This makes the female rats less active in that period.

The weight of an average rat baby is just several grams (3 to 6, depending on the species), and they are born blind, naked and completely helpless. They typically open their eyes after about 6 days and they start growing fur at the start of the 3rd week (close to the end of the weaning period). The weight of a rat at weaning is several dozen grams. Depending on the exact species, an adult rat can reach anywhere between several inches to the monster size of 10+ inches.

Adolescent rats are obviously smaller and can sometimes be mistaken for mice, so it’s important to try and identify them properly so that you know whether you’re dealing with rats or mice.


While they don’t reproduce and grow as quickly as mice and they tend to live a bit longer, rats are still among the faster living (and dying) animals out there. This means that when left unchecked their rapid reproduction cycle can quickly grow out of our control and rats can deal serious damage to our property and sometimes even drive entire families out of their homes. This makes it crucial that homeowners and commercial property owners take good care of their facilities, take preventive measures against rats, do routine check-ups for rat presence, and act as quickly and as extensively as possible when such presence is found.

Submit a comment

Your email address will not be published*