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How Big Do Ferrets Get? [Average Growth Rate & Expectations]

Ferrets make great pets; they are playful, friendly, loving, and fiercely loyal to their owners. But what about their size? How big do ferrets ultimately get and what factors and considerations do you need to take into account regarding their growth? I decided to conduct some thorough research on the topic to help you get a better understanding and to set your expectations.

So, how big do ferrets get? Male ferrets (Hobs) reach an average length of 38cms, 15 inches (not including the tail), and weigh somewhere between 0.7 to 2 kilograms when they reach full adult maturity. Female ferrets (Jills) will reach around 35cm, 13.5 inches in length (including the tail), and will weigh around 0.6-1kg at full adult maturity. These mammals are sexually dimorphic; males are considerably larger than their female counterparts by the time they reach their full size.

These Mustelids are not considered large creatures, but they do need plenty of room to maneuver; they are very active and need lots of exercise.

If you’re wondering about your home and setup, you’ll be pleased to learn that they can live comfortably in an apartment as well as a large house.

Let us now explore the topic further so that you can get a better understanding of their growth rate, size, when you can expect them to stop growing, and other information regarding their average lifespan.

Ferret Growth Rate

While ferrets are naturally slender, they grow at an incredibly fast rate. Just breaking it all down will give you an understanding of how quickly this really is.

They double their weight within the first five days of their birth, and by day ten their birth weight will have been tripled to around 30 grams.

You can expect your ferret to gain 4 grams every day during the second week of their life, then 6 grams every day in the third week. They are ten times their birth weight by week 3.

In week 5, males develop broader heads and are generally bigger than their female counterparts. This is when the two genders start to really be distinguished from one another.

At 16 weeks, ferrets reach their full adult weight. Adult males reach a length of about 38 cms/15 inches ( not including the tail ) females reach an average length of 35cms, 13.5 inches (this includes the tail).

To get a better picture of how quickly these animals grow, review the information on the table below:

Ferret Growth Rate, By Gender

AgeFemale Weight/LengthMale Weight/Length
Newborn8-12 Grams8-12 Grams
1 Week30 Grams30 Grams
2 Weeks60-70 Grams60-70 Grams
3 Weeks75-95 Grams100 Grams
4 Weeks100-150 Grams125-200 Grams
5-6 Weeks180-200 Grams, 12 Inches (Not Including The Tail)230-250 Grams, 12 Inches (Not Including The Tail)
6-8 Weeks~300-500 Grams ~400-500 Grams
Week 16600-900 Grams, 13.5 Inches (Not Including The Tail)1000-2000 Grams, 15 Inches (Not Including The Tail)

When purchasing a cage, you must consider their age, present and future size when they reach full maturity.

While gender plays a crucial role in determining their full growth size, you should also consider the fact that ferrets need the companionship of other ferrets.

Getting a double story cage, like this award-winning one on Amazon, will ensure you can house two ferrets, plus give them plenty of opportunities to remain active.

As an owner, you must remember that these Mustelids grow very quickly; so be sure to enjoy the kitt stage while it lasts.

Ferrets are considered midlife at three years of age so there is even more reason in which to do so.

When Do Ferrets Stop Growing?

Ferrets stop growing and reach their full size at four months of age. Similarly, this is the stage of life that ferrets can begin to reproduce. They continue to age quickly, and at three years old, ferrets are considered to be in midlife.

Ferrets have rapid pregnancies with a gestation period of only 42 days. Kitts are born deaf, blind, and helpless; so need mothering in their early stages of life.

Two weeks after their birth, baby teeth emerge, and at seven weeks, their permanent teeth come through. At four months, hobs (male ferret) weigh between 2-2.5 pounds, whereas jills (female ferret) are smaller at 1-1.5 pounds.

Despite being at their full size, these mammals are not yet sexually mature.

Jills enter sexual maturity between 5 to 8 months old, and hobs begin sexual maturity between 6 to 8 months old.

Unless you are looking to reproduce, spaying or neutering your pet is considered crucial by many vets; it is known to extend their lifespan.

Neutering is considered especially advantageous to females who otherwise would be more prone to aplastic anemia (shutdown in production of new red blood cells); they are less likely to develop this condition if they do not breed.

Most pet stores and breeders sell ferrets previously neutered; otherwise, it is a very straightforward procedure. You will, of course, need to contact a vet who will be able to offer such services.

How Long Are Ferrets?

Ferrets are sexually dimorphic, meaning that males and females will develop different characteristics beyond their sexual organs alone. Growth size is one of these areas.

Healthy males will reach an average length of 38 cms as adults (not including the tail). Females are smaller and reach an average length of 35 cms as adults (including the tail ).

Ferrets have a typical Mustelid body shape in that it is long and slender. These animals are domesticated from the European polecat.

The primary reason these mammals were domesticated is unclear, but more than likely, they were bred for hunting purposes.

Ferreting is controversial due to potential damage to agriculture: however, many countries continue to use ferrets for hunting (especially for hunting rabbits).

This includes the United Kingdom. It is believed that the Romans were the first to breed ferrets for hunting.

These Mustelids, therefore, have developed long and slender physiques, equipping them with the ability to go down holes and chase moles, rodents, and rabbits out of their burrows.

Ferrets require a cage to suit their long bodies. At a minimum, it must be 18 inches in length and depth, and 30 inches in width.

These mammals sure love to exercise, so their enclosures require more than one level.

Ferret Lifespan

On average, ferrets live between 6 to 10 years. This is for a healthy ferret that has not inherited any unfortunate trait or characteristic via its genetics.

If you feed the correct diet, this will improve their chances of living to old age and remaining robust and healthy throughout the years in which they do live.

Ferrets must eat meat; they are strict carnivores. It is far easier today to obtain their food than ten or twenty years ago, and it is available in both dried and canned form.

You can purchase their food from pet stores, vets, and online. My favorite go-to is the Wysong brand which I get for an excellent price on Amazon.

Sadly, ferrets are prone to numerous diseases, particularly adrenal diseases and cancer. Therefore, you must locate a vet who is knowledgeable in ferret care.

It’s also good to do this ahead of time and before any complications or health issues begin to arise.

By the time your ferret is three years old, you can expect to take them to more than just one annual check-up. Three is the age that many ferret diseases start to appear.

Ferrets have a terrible habit of chewing and swallowing inedible and often harmful objects. This habit of theirs often leads to gastrointestinal blockages. It is imperative that you ferret-proof all areas that your pet accesses, never let your ferret out without supervision.

Be sure to tidy up ahead of any playtime, and always be on the lookout for potential issues and harmful objects.

Some are more obvious than others and ferrets of course are nimble and can get into tiny little spaces you may not have expected.


Ferrets make excellent pets; many owners develop very tight bonds with these animals as they do require a lot of their owner’s time and care.

If you were here looking for information regarding their size, it’s important to note that they are not large-sized pets by any means.

They are, however, very energetic and need lots of space to exercise. They can get lonely, so it is advised to get two or more, they really benefit from the company.

Sadly, their time with you is short as they live an average of 6 to 10 years. It’s important to enjoy the time you have with them as they will not be around as long as other potential pets.

With all this being said, do not let their needs, requirements, risk of illness, and short lifespan deter you from getting a ferret. They can make great companions and are a pleasure to care for.

Want to learn more about ferrets and their interesting traits and behaviors? Then be sure to read my guides below: