How Old Are Guinea Pigs in Human Years? (6 Things To Know!)

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Just like humans, guinea pigs can also get old. In fact, they might not show obvious signs most of the time.

As a guinea pig owner, how do you exactly know your guinea pig’s age? 

Quick answer:

A year-old guinea pig is equivalent to 10 years old in human years (estimated).

For example, if your pet is 5 or 7 years old, they’ve become 50 or 70 years old in human years. 

These animals tend to achieve a lot within their lifetime of 5-8 years. 

But, while the human years is not a proven method of measuring age, it gives us the understanding that people and animals can age.

Now, you understand how old a guinea pig is in human years, read on to find out more about their age.

How old is a 4, 5, 6, 7, 8 year-old guinea pig in Human years?

Despite the different charts online about the guinea pigs’ age and its equivalence to human years, I’ve developed a calculation below.

And this calculation is based on the usage of a few veterinary clinics.

It shows that a pig’s 10 years is equivalent to a human’s 1 year.

However, let’s see the guinea pigs’ age based on the observations of the vet. clinics stated above. 

Human Years equivalenceGuinea Pigs years 
4 years40 years
5 years50 years
6 years60 years
7 years70 years
8 years80 years

Guinea Pig Age Calculator

A guinea pig’s age calculator is a free and simple tool used to convert the animal’s age into human years.

To better appreciate the youth or old age of a guinea pig, it’s okay to find out the human equivalent of their age.

This is done by applying a simple mathematical formula, even though no formula can completely tell the age.

What the calculator does is give you an estimation of the guinea pig’s age in human years.


Bodily and behavioral changes in humans are different from guinea pigs as they get older.

Notwithstanding, the calculator follows the ages that expert veterinarians have correlated and stated in human years.

How to figure out your guinea pig’s age?

Guinea pigs are interesting and fun animals, which makes them a great choice of pet for everyone.

Nevertheless, you only know their age when you buy them from breeders who know their date of birth.

Otherwise, you have to go through the hassle to figure it out.

Luckily, you can find out their age by observing them each day.

Over time, they begin to show off the signs of aging.

Below are the life stages of guinea pigs together with the symptoms that will help you figure out their age at each stage.

1 – 11 Months Old

A greyish 1- 11 months old guinea pig.
Credit to Pernille Westh

Guinea pigs often have rapid growth during their first year of life. As the months pass, their size changes. 

Their nails become pointed, and transparent and turn yellow as they thicken. 

Young guinea pigs also grow little white teeth at this age.

All through the first year, their teeth’ color does not change, it remains white, sharp, and delicate. 

At about 3 months old, a guinea pig in good shape should weigh up to 18 ounces.

But when it turns one year old, its weight should increase to about 30 – 40 ounces.

Also, at this phase, guinea pigs normally have small backsides, but this will change as they grow older.

1 – 5 Years Old

A 1-5 years old guinea pig now black in color
Credit to Pezibear

In this stage, their sharp white teeth become duller and begin to crack. 

In addition to these, the pig’s nails turn more yellow and are extremely hard.

Their muscular tone changes, especially when they are 1 – 3 years old. At this time, the tone is better than when they are 4 – 5 years old.

Mostly, when guinea pigs turn 2 years old, they stop adding weight.

5 – 7 Years Old

5 -7 years old white guinea pig with black patches.
Credit to MarketJirmann

At this level, a guinea pig is fully grown and is said to be in its senior years. 

Here, you will observe that your pig’s nails become thicker and more brittle. Now they find it difficult to play with toys.

Guinea pigs will also find it challenging to go around their environment because their speed decreases.

Surprisingly, their hair thins out compared to their younger age, while their rear end becomes bigger.

Other Methods To Figure Out Your Pet’s Age

An alternative way to find out a guinea pig’s age is to visit a veterinary doctor.

He/She will carry out thorough examinations on the animal and is in a better position to tell you their age. 

What is considered old for a guinea pig’s age?

The moment a guinea pig turns more than 5 years old, it is considered old.

At this phase, their requirements differ among individuals. 

To ensure that your pet is happy and healthy, it’s important to take it to a veterinarian for a yearly check-up.

Just the same way other pets love moving around their vicinity, older guinea pigs need activities (minor exercises) to keep them going.

But this need is not necessary to test their capacities as they’ve become older and weaker. 

When your pet becomes a senior guinea pig, make sure you create a routine for its wellness check

How old is the oldest guinea pig?

The oldest guinea pig according to the Guinness Book of World Records was 15 years old.

Although the average lifespan of these pets is 5-7 years, a few of them have lived longer than that.

Final Thoughts

In summary, a one-year-old guinea pig in human years is around 10 years old. That means 4 and 5 human years is equivalent to 40 and 50 piggy years.

Veterinarians have established this age using the guinea pigs’ age calculator which converts it to human years.

To figure out the age of a guinea pig, all you need to do is carefully watch its growth and the changes that come with it. Afterward, use the guinea pig’s calculator to estimate the age.

Once a guinea pig is more than 5 years old, it is regarded as old.

And the oldest guinea pig that ever lived was 15 years old, breaking the limits of their 5-7 years lifespan.

You’ve learned everything about the guinea pigs’ age in human years, would you also love to learn if they understand humans?

Read our article “Can Guinea Pigs Understand Humans?” To learn more.

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