How to Tell How Old a Guinea Pig Is


Image Source

Whether you are quite an old pet parent or are new to this, guinea pigs are the perfect pet options for you. These fun little animals are easy to take care of, especially when compared to cats and dogs. Since they are easy to handle, guinea pigs make excellent pet choices for young children.

It can be, however, a little tricky to know exactly how to tell how old a guinea pig is. Unless you have purchased your guinea pig from a breeder who knows the exact birthday of the little animal, it may not be easy to know your little pet’s age.

If you want to know how to tell how old a guinea pig is, you need to partake in a few investigations. It is not very difficult as guinea pigs show various signs as they keep aging, which makes it easier for you to tell at what stage your guinea pig is in.

Do you want to learn how to tell how old a guinea pig is? Here is a quick and easy guide that will help you figure this out in a jiffy.

Different Stages In A Guinea Pig’s Life

Stage 1: 1 to 11 months

During their first year into this world, guinea pigs grow quite rapidly. You will notice a considerable difference in their body size with every passing month. You will also notice that the growth becomes a little less noticeable once they reach about one year.

Another thing that will help ascertain that your guinea pig is still under a year old are their nails. During their first year, they have nails that are pointy and translucent. These begin to thicken and become yellow as they grow.

Another way to know how to tell how old a guinea pig is to look at their teeth.

Guinea pigs who are under one year old have small, white teeth. These start growing a little while after they are born.

Throughout their first year, the teeth will remain thin, white, and sharp.

Guinea pigs also weigh around 18 ounces (0.68 kg) during their first three months, if they are healthy.

They may reach anywhere between 30 and 40 ounces (1.51 kg) when they turn one year old.

Stage 2: 1 year to 5 years

Once your guinea pig crosses one year, there are other subtle signs that can help you figure out how to tell how old a guinea pig is.

The changes are subtle, so you need to look out for them. It can be slightly harder to notice these changes as compared to when they were young.

As they reach an older stage, the teeth will lose their original whiteness and become duller. You can tell that your guinea pig has reached around 5 years of age if their teeth are very dull.

When they age more, the teeth of guinea pigs start to chip or break. This can help you know how to tell how old a guinea pig is.

The nails also start getting more yellow and brittle with every passing year.

When guinea pigs are between one and three years of age, their muscle tone is slightly better. This changes when they are four or five years.

Guinea pigs also stop gaining weight when they are two years old.

Stage 3: 5 years to 7 years

When your guinea pigs reach five years to seven years, they will be considered seniors. There are some obvious changes that can help you figure out if your fur baby has reached this stage.

First, the nails will get thick and brittle. These also lose their effectiveness when it comes to playing with toys. They may also not be able to navigate their surroundings like they could when they were younger.

The backsides also get wider. The movements become very slow. You will also notice that their hair starts thinning out.

Factors That You Need To Look Out For

You already know about the different stages in a guinea pig’s life. Here are some factors that you are already aware of. We have explained them in brief as ways that can help you figure out how to tell how old a guinea pig is:


In the case of a young guinea pig, the nails are short and pointy. These nails are also translucent with a very slight pigment to them.

The nails will start getting thicker as they reach one year. These nails will also become rounder in diameter.

The nails will also become opaque. It will forego its previous translucency. You will also notice that the nails develop a yellow color. This is an indication of its aging process.

Checking the nails is a very important factor in estimating the age of your guinea pig.


The next factor to look out for is the teeth. Guinea pigs have small and white teeth when they are born. These keep growing throughout your pet’s lifetime.

However, with age, the teeth start chipping and breaking. To help your guinea pig wear out their teeth, you can feed them a variety of fresh grasses.

Doing this will be of great benefit to your guinea pig. This will prevent their teeth from overgrowing. Chewing and gnawing on food helps the teeth to trim off.


You can also easily tell the age of the guinea pig by looking at its body. This depends largely on the breed of the guinea pig.

At three months old, your little fur baby can weigh about 18 ounces (0.68 kg). This keeps increasing majorly until it reaches one year.

In females, you can notice that the growth leads to a spread in their hind ends.

In males, you notice that their testicles are highly visible by the time they reach six weeks of age.

Image Source

What Is Normal For Guinea Pigs?

When it comes to weight, shape, and hair length, these differ from one guinea pig to the other.

You cannot only rely on looks to figure out how to tell how old a guinea pig is.

Adult guinea pigs are between 10 inches (25.4 cm) and 12 inches (30.48 cm) long and could weigh anywhere between two and three pounds. If your guinea pig is smaller or larger, you need not worry. It is not unhealthy or abnormal.

You must weigh your guinea pig every week to rule out any health issues. This will also help you identify any health problems.

The average lifespan of a guinea pig is between five and seven years. There is no hard and fast rule about when a guinea pig reaches its golden age. As per most vets, guinea pigs touch this stage when they reach four years old. You need to understand that guinea pigs age differently and the rate at which they age is also quite different.

Signs of aging also appear at different times, depending on the guinea pig. For some, these signs start appearing early and for others, they may start showing quite late.

As they age, guinea pigs also become less active. They may develop medical conditions such as arthritis. They may also develop cataracts in their eyes.

Can Guinea Pigs Reach The Age of Eight Years?

As already mentioned, the average life span of a guinea pig is between five and seven years. If your guinea pig crosses that age and enters its eighth year, it is considered to be an extremely rare case.

To keep your guinea pig healthy, you can ensure to feed it with healthy foods. This also helps to extend the life expectancy of your little fur baby.

The key to a longer life for your guinea pig is you. It all depends on how deeply you take care of your pet.

How Old is a Guinea Pig in Human Years?

As with other pets, you can calculate a guinea pig’s age in human years. One guinea pig year is equivalent to 18 human years.

This means that if your guinea pig has reached its seventh year, it is equivalent to 126 human years.

When your guinea pig reaches its senior years, you need to take special care of it. You need to take care of all their unique needs.

You must also know that the golden years of guinea pigs are highly crucial. It is advisable that you bond very well with your little fur baby until the last minute.


Is being four years too old for a guinea pig?

It is recommended that a guinea pig reproduces at five to six months. It is believed that a guinea pig is an adult and is fully grown when they reach 14 months. Four years is what vets believe to be the golden year for the guinea pig. Also, the average life span for them is between four and seven years.

What is the average age of guinea pigs at the pet store?

The guinea pigs that you find at pet stores are usually between eight and 12 weeks.

What can you feed your three months old guinea pig?

This is the time when you can introduce your guinea pigs to timothy and oaten hay. You can also give them chaff and pellets, along with small amounts of green vegetables. Also, give them water in a shallow dish.

A mother guinea pig usually ensures that she is feeding her babies for about three to six weeks. After this, they gradually decrease the number of times that they feed their little ones.

You May Also Like