First and foremost, a cat purrs because it feels good. When your cat is lying in your lap with half-closed eyes and a deep, steady rumble in its chest, it is communicating security and well-being. But purring is not only an expression of contentment. Cats also purr when they are stressed, nervous, ill or in pain, and that is precisely why the sound is more complex than most people think. To understand why a cat purrs, it helps to look both at the mechanism behind the sound and at the situations in which it occurs.
How the purring sound is created in the cat's body
The purr is not produced in the lungs, but in the larynx. The brain sends rapid, rhythmic signals to the muscles around the cat's vocal cords, causing them to contract and relax many times per second. When the air passes the vocal folds during both inhalation and exhalation, they begin to vibrate, and it is these vibrations that create the characteristic, uninterrupted rumble. Because the sound is produced on both inhalation and exhalation, a cat can purr almost without pause, which sets purring apart from most other sounds an animal makes.
The frequency is typically low, in the range of 25 to 150 oscillations per second. This is one of the reasons the purr feels so deep and soothing when you have the cat close to you. A cat learns to purr within the very first days of life, long before it can see or hear properly, which says something about how fundamental the sound is to the species.
Why does a cat purr out of well-being and security?
The most common reason is the one most people know: the cat is content. When your cat is being cuddled, is lying warm and secure or has just had a good meal, it purrs to signal calm and contentment. In adult cats, purring is also a social sound between cats that know each other, and between cat and human. It functions as a kind of confirmation that everything is as it should be and that the situation is peaceful.
You can often read the content purr from the rest of the body language. Relaxed ears, half-closed eyes, a soft body and possibly a slowly swishing or completely still tail point to a cat that feels good. If you want to get better at interpreting the signals your cat sends with its tail, you can read more in the guide what does it mean when a cat swishes its tail.
The purr between kitten and mother
Purring begins in kittenhood and from the very start has a wholly practical function. A newborn kitten is born blind and deaf, but can feel vibrations. When the mother purrs, it helps the kittens find their way to her and nestle up to the warmth and the milk. The kittens, in turn, purr while they nurse, thereby telling the mother that they feel safe and are getting enough to eat.
This early connection between purring and something good, namely closeness, warmth and food, is probably part of the explanation for why adult cats keep purring in calm, pleasant situations for the rest of their lives. If you want to know more about kittens' development and needs during the first weeks of life, we have gathered our advice in the guide the best start in life for your kitten.
When the cat purrs out of stress, anxiety or pain
Here purring becomes more complicated, because it is not always a sign that the cat feels good. Many cats purr when they are frightened or stressed, for example at the vet, during a car ride or in a situation where they feel insecure. A cat may also purr when it is ill, gets injured or is in pain. In those cases, purring probably functions as a form of self-soothing, somewhat in the same way as a person comforting themselves in a difficult situation.
Researchers have put forward a hypothesis that the low frequencies in purring may have a soothing effect on the body, among other things on bones and tissue. This is still a debated area, and one should be careful about drawing firm conclusions. But it underlines that purring is not only about joy, and that it can be the cat's way of coping with discomfort.
This is precisely why it is important not to interpret purring in isolation. If your cat purrs but at the same time seems withdrawn, eats less, hides or has a tense posture, it may be a sign that something is wrong. If you notice that kind of change, you should contact your vet, who can assess whether there is an underlying health issue.
Purring as a plea for attention and food
Cats are skilled at communicating with us, and some have learned to use purring strategically. A number of cats develop a special purr that they use when they want something, typically food or attention. This form is often mixed with a sound that, in terms of frequency, resembles a baby's cry, and it is hard for humans to ignore. That is why it works well when the cat wants to get you up in the morning or wants its bowl filled.
You can often hear the difference if you listen closely. The pure, content purr is deeper and more uniform, while the demanding purr has a sharper, more insistent undertone. Understanding the difference makes it easier to read what your cat is actually asking for in the situation.
How to read your cat's purring correctly
Because purring can mean several different things, the most important rule is to read the whole cat and not just the sound. Look at the eyes, the ears, the tail and the posture, and take the situation into account. A cat that purrs relaxed on the sofa after a meal is in all likelihood feeling good. A cat that purrs curled up in a carrier on the way to the vet, on the other hand, is probably doing so to calm itself.
Calm, predictability and secure surroundings in everyday life provide the best conditions for the good, content purr. A fixed daily rhythm, familiar surroundings and high-quality meals all contribute to a cat that thrives. At ESSENTIAL FOODS we compose meals with fresh produce and human-grade ingredients, and if you want to find the right one for your particular cat, you can explore the selection in the cat meals collection homepage. If you are in doubt about what suits your cat's age and needs best, our nutrition advisors are ready on phone, chat and email with guidance on feeding and nutrition.
So a cat purrs for many reasons, and in the vast majority of cases because it feels good and feels safe in your company. But purring is also a tool the cat uses to calm itself, communicate with us and ask for what it needs. The better you become at reading the rest of the body together with the sound, the clearer it becomes what your cat is actually telling you every time it begins to purr.