Ermine vs Weasel: 4 Ways They Are Different

Written by Kyle Glatz
Published: August 12, 2022
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Understanding animal nomenclature is difficult because so many of the same creatures reside in the same phylogenetic family and look so much alike. That is the case with the ermine vs weasel, two groups of mammals that are closely related but ultimately have some differences. Today, we’re going to explore these differences in greater detail and help you understand what makes each of them unique.

Comparing an Ermine and a Weasel

Weasels are different from ermines in size and methodology.
Phylogenetic Group– Family Mustelidae
– Genus Mustela
– Species M. erminea
– Several subspecies
– May be called stoat, short-tailed weasel, or ermine
– Family Mustelidae
– Genus Mustela
– Species: 10 different species
– The term weasel is typically applied to the Mustela nivalis, or the least weasel.
SizeWeight: 6 to 9 oz
Length: 7 to 13 inches
Weight: 1 to 8 oz
Length: 5-10 inches
Range– North America
– Europe
– Northern Asia
– New Zealand
– North America
– Europe
– Northern Africa
– Northern Asia
Morphology– Pure white underside
– Thicker body
– Black tip on its tail        
– Has a longer tail than the least weasel
– Tail measures about 1/3 of their body length
– Fur can turn white in the winter
– May have brown patches on the throat
– Brown top on its tail
– Stubby tail
– Slender body
– Stays brown all year

The 4 Key Differences Between an Ermine vs a Weasel

mink vs weasel

Weasels are wild carnivores that weigh very little.

©Stephan Morris/

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The greatest differences between an ermine and a weasel are their size and morphology. Ermines, also called stoats, are small mammals that weigh between 6 and 9 ounces and grow up to 13 inches. They have bushy tails, thick bodies, a black tip on their tail, and fur that can turn snow white in the winter. Weasels only weigh up to 8 ounces and measure 10 inches long. They have a stubby, brown tail, a slender body, and fur that stays brown all year long.

These are the most noticeable differences and are the most useful ways at helping people tell these animals apart. We’re going to look closer at the four key differences between an ermine and a weasel.

Ermine vs Weasel: Species

Before we look into the main differences between ermines and weasels, we need to consider the phylogenetic groups of each creature.

The ermine comes from the family Mustelidae and the genus Mustela. Although many animals bear the name “ermine”, it refers most specifically to the M. erminea, an animal with many different subspecies. Typically, the names attached to the ermine include stoat and short-tailed weasel.

However, the weasel belongs to the family Mustelidae and the genus Mustela. Although there are 16 different species in the Mustela genus. The term weasel is typically attached to Mustela nivalis, also referred to as the least weasel or common weasel.

Thus, it’s fair to say that all ermines, or stoats, are part of the family that is considered weasels, and they are closely related. Yet, they have enough differences to tell them apart.

Ermine vs Weasel: Size

mink vs weasel

Most ermines grow up to 13 inches long, and a lot of their length comes from their tail.

©Bildagentur Zoonar GmbH/

Ermines are larger than weasels. The average ermine weighs between 6 and 9 ounces and measures between 7 and 13 inches in length, with about a third of their total body length being their tail.

Weasels vary in weight between 1 to 8 ounces, and they can measure anywhere from 5 to 10 inches in length, with their tail contributing far less to their overall length compared to the ermine.

Neither of these animals is particularly large. However, when you see them side by side, it’s easy to tell the difference between the animals.

Ermine vs Weasel: Range

Both ermines and weasels have large ranges around the world, and their territories overlap in several areas. The ermine can be found in the northern hemisphere for the most part. They live in North America, Europe, and Northern Asia, including Russia.

Interestingly, ermines, or stoats, were brought to New Zealand as part of an effort to control the rabbits that were destroying sheep pastures. Unfortunately, they instead developed a taste for the birds of the nation. As a result, they have become an unwanted pest and remain one of the number-one predators for endangered animals throughout New Zealand.

The least weasel has a range that includes most of North America, Europe, and northern Asia. They are also found in the northwestern top of Africa, a place the animals most likely entered via Spain or Italy.

However, all the different species of weasels combined have a larger range that includes Central America and parts of South America.

Ermine vs Weasel: Morphology

stoat vs weasel

Ermines can change their fur color, but weasels cannot.

©Jukka Jantunen/

The ermine and weasel are both small, long, brown creatures. While they have many similarities, they also have several unique qualities that you can use to tell them apart. For example, the ermine has a pure white underside, but the weasel has brown patches by its throat.

The ermine also has a thicker body than the weasel which is a thin creature. The easiest way to tell the two animals apart lies in their tail. The ermine has a long, bushy tail that has a black tip. In fact, their tail can make up as much as 1/3 of their total body length. Yet, the weasel’s tail is short, stubby, and always brown. Other species of weasels, like the long-tailed weasel, have a much longer tail, so they are harder to differentiate from an ermine.

Lastly, some ermines can turn from brown to white to suit the winter landscape. Their fur helps them dodge predators by blending in with the snow in northern areas. However, the weasel is always brown and only has a white underside. Weasels lack the ability to change their color throughout the seasons.

By looking at the tails, color, and body shape of the ermine and weasel, it’s easy to tell them apart. Now that you know the difference between an ermine vs weasel, you should be able to identify them when you’re out in the wild. The chances are that you will only catch a glance of these animals, though. They are not fans of interacting with potential predators.

The photo featured at the top of this post is © Ghost Bear/

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About the Author

Kyle Glatz is a writer at A-Z-Animals where his primary focus is on geography and mammals. Kyle has been writing for researching and writing about animals and numerous other topics for 10 years, and he holds a Bachelor's Degree in English and Education from Rowan University. A resident of New Jersey, Kyle enjoys reading, writing, and playing video games.

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