Why do cats purr?
Purring is a low, steady rumble from the throat: mostly about feeling relaxed or close, sometimes a request or a way to calm down.
Cats purr most often when they are relaxed and close to someone they trust. They also purr to ask for food or attention, and sometimes to calm themselves when stressed, afraid or ill. So a purr alone does not tell you how your cat feels: look at its body and where it is too.
Usually normal. Purring is normal and usually a good sign, but it is not proof that your cat is happy. Look at the whole cat.
How do cats purr?
- 1
The sound comes from the voice box
The purr is made in the voice box: the vocal folds vibrate as air passes. The mouth stays closed and the sound comes out of the mouth and nose. It is strongest right in front of the muzzle. That is why you hear and feel it so well when your face is close.
- 2
A very low pitch
A cat purrs at about 25 Hz, far below the lowest human voice. Measured house cats were between 21 and 27 Hz, and every cat sounds a little different. You often read 25 to 150 Hz, but measurements of living cats stay around 20 to 30 Hz. Size and age do not make the pitch higher or lower.
- 3
In and out, without a pause
Most animals only make sounds when they breathe out. A cat purrs on both the in-breath and the out-breath. That is why the sound never seems to stop.
- 4
The voice box can do it by itself
In 2023 researchers in Vienna blew warm, moist air through cat voice boxes. The vocal folds then vibrated at purring speed by themselves, without nerves or muscles. Small pads in the vocal folds probably make that low vibration possible.
- 5
The brain switches it on
For a long time we thought muscles in the throat twitch 20 to 30 times a second. That turns out not to be needed for the sound, but it may still help. In a living cat the brain switches the purr on and off. Whether a cat purrs on purpose, nobody knows yet.
- 6
Which cats purr
House cats, cheetahs, cougars, lynx and most other small cats purr. Lions, tigers, leopards and jaguars roar. They make at most short purr-like sounds on the out-breath. Outside the cat family, only genets and their relatives truly purr like a cat.
What does each kind of purr mean?
Steady soft purr, eyes half closed
Relaxed and comfortable. Often it wants the contact to go on.
RelaxedGo ahead and say helloPurr with a high, urgent cry
It is asking for food or attention, often near meal time or by the bowl.
HappyGo ahead and say helloSoft purr while rubbing against you
It is asking for petting or company.
HappyGo ahead and say helloLoud purr with kneading and drooling
It is really enjoying the stroking. Watch out though: it can sometimes become too much, and then it bites.
HappyTake it slowlyPurr with meows and flat ears
Stressed or unsure, for example in the carrier or at the vet. It is calming itself.
TenseTake it slowlyConstant or unusually loud purr
Together with hiding, not eating or hard breathing, it may be in pain or ill. The purr alone does not say which.
TenseTake it slowlySoft purr while suckling
From kitten and mother: all is well, we are together.
RelaxedGo ahead and say helloCalm purr towards a familiar cat
Friendly: I mean no harm. Often while grooming the other cat.
RelaxedGo ahead and say helloShort soft purr-trill when it sees you
Most likely a greeting.
HappyGo ahead and say hello
Why do cats purr? The main reasons
Feeling relaxed and safe (happy, mostly)
Most commonThis is the most common reason. A cat purrs when it is settled on a lap, being stroked, lying in the sun, eating or just resting. Its body is loose, its eyes half closed and its tail still.
How to tell- Loose, relaxed body
- Eyes half closed
- Steady, soft purr
Staying close to someone
CommonPurring is also a social sound. A cat uses it to make and keep contact with you or with a cat it knows. For example when you come home, or when two cats groom each other. It also says: I mean no harm.
How to tell- Purrs when greeting you
- Rubs against your legs
- Purrs while grooming another cat
Asking for food or attention
CommonMany cats purr to get something. A request purr hides a higher, crying sound inside the rumble, a bit like a crying baby. That makes it hard for people to ignore. If you respond to it, your cat will do it more.
How to tell- A higher, urgent sound inside the purr
- Walks back and forth between you and the bowl
- Around meal times or early in the morning
Kitten and mother staying in touch
In every litterKittens purr in their first days, while they suckle and before they can see or hear. That helps the mother find them and tells her all is well. The mother purrs back to reassure them.
How to tell- Purring while suckling
- Mother purrs while nursing
Calming itself when stressed or afraid
Common in stressful momentsCats also purr in the carrier, at the vet or after a fright. That purr probably helps them settle. Its body shows that it feels tense: ears flat or sideways, wide eyes, often meowing too.
How to tell- Purrs in the carrier or at the vet
- Ears flat or sideways, wide eyes
- Purring mixed with meows
Coping with pain or illness
UncommonA cat can also purr when it is in pain or ill. The purr may help it, but it does not mean the cat feels comfortable. This is less common. Does your cat suddenly purr much more or louder than usual, and does it hide or not eat? Then call the vet.
How to tell- Purrs while hiding or not eating
- Sits hunched or moves stiffly
- Breathes fast or hard
When do cats purr, and what does it mean?
- Your cat purrs when you stroke or pet it
- Most cats purr when stroked, and usually they enjoy it. Especially if your cat leans into your hand and stays loose. Does its body stiffen, its tail lash or its skin ripple? Then stop. Which spots it likes differs from cat to cat.
- Your cat purrs on your lap or the bed
- A cat that purrs on you feels safe and warm with you and keeps in touch. Often it kneads too. It is simply affection.
- Purring at meal time
- Many cats purr while eating, perhaps a habit from suckling as a kitten. Before meals the purr is often a request. Does your cat suddenly ask for food much more or less often? Then keep an eye on its appetite and health.
- Purring at the vet or in the carrier
- Does your cat purr and meow at the vet or in the carrier? Then it is usually tense, not content. It is calming itself. So it does not mean all is fine.
- Purring while giving birth
- A mother cat often purrs between contractions. It probably calms her and may help with the pain.
- Purring when hurt or ill
- Cats also purr when they are in pain, recovering from an injury or very ill. Then the purr is a way of coping, not a sign that the cat feels comfortable.
- Your cat does not purr
- Not every healthy cat purrs. Some cats purr so softly that you can only feel it. Does your cat show it likes you in other ways, such as rubbing its head on you, leaning against you or sitting close? Then all is usually well. Kittens taken from their mother very young sometimes purr less.
- Your cat has stopped purring
- A cat that always purred and stops may be stressed, in pain (a sore throat makes purring hurt) or simply getting older. Watch its eating, moving and hiding. Does it stop suddenly and eat less, rest more, or have diarrhoea or sore eyes? Then call the vet.
How to read your cat's purr
- 1
Look at the whole cat, not only the sound: body, ears, eyes, whiskers and where it is.
The same purr means rest on the sofa and stress at the vet. Only the situation shows the difference.
- 2
Pause now and then while petting and see whether it leans towards your hand and stays relaxed.
That way your cat decides, it stays pleasant and you avoid a bite when it gets too much.
- 3
Learn what is normal for your cat: how often and how loudly it purrs.
A change from its own normal tells you more than any fixed rule.
- 4
At the vet or in a carrier: speak softly, cover the carrier and keep things quiet, even if it purrs.
There it is probably calming itself with the purr. It still needs calm.
- 5
Has your cat stopped purring or does it purr very differently? Watch its eating, moving and hiding for a few days, and call the vet if more changes.
Cats hide illness well. A change in behaviour is sometimes the only sign of pain.
- 6
Does your cat not purr? Then look for its other ways of showing it feels good: rubbing its head on you, leaning against you, sitting close, slow blinks.
Purring is only one signal. Many healthy cats purr little or never.
Better not
- Do not keep stroking because it purrs, when it stiffens, lashes its tail, flattens its ears or wants to leave.A purr does not mean it wants more. When it gets too much, it may bite.
- Do not wait in the hope that an injured or sick cat will purr itself better.That purring heals is not proven. A purring cat can still be in pain.
- Do not worry that a cat that never purrs is unhappy, and do not try to make it purr.Many healthy cats purr little or never. Look at the rest of its behaviour.
- Do not ignore a new, constant or much louder purr when your cat also hides, eats less or moves differently.That can be a sign of pain or illness.
When to see a vet?
Purring alone is not a reason to see a vet. Do go when the purr comes with other changes, and go the same day for breathing trouble, severe pain or a male cat that strains in the litter box with little or no urine. Has your cat stopped purring and does it eat less or hide? Then have it checked.
- Open-mouth breathing, fast or hard breathing (more than 30 breaths a minute at rest), collapsing or being very weak, even while purring: see a vet the same day.
- It cries out in pain, cannot use a leg, or a male cat strains in the litter box with little or no urine: the same day.
- It has not eaten for 24 hours or more, hides, limps or keeps licking one spot, and purrs as well.
- The purr is new, constant or clearly louder than normal, and its behaviour changes too: hiding, less active, eating less or not wanting to jump.
- It suddenly stops purring and eats less, rests more, vomits, or has diarrhoea or sore eyes.
- It purrs and also has diarrhoea, vomits, coughs or sneezes.
What research says
A cat's voice box can purr by itself
Eight voice boxes from domestic cats that had died vibrated at 25 to 30 Hz when warm, moist air went through them, without nerves or muscles. Pads of connective tissue up to 4 mm across in the vocal folds probably make the low pitch possible. How a living cat starts and steers its purr, the study did not show.
Herbst and colleagues, University of Veterinary Medicine Vienna, 2023Request purrs hide a cry
Recordings of ten cats showed an extra high sound inside the purr when they asked for food, close to the sound of a crying baby. Fifty listeners, including people without a cat, found these purrs more urgent and less pleasant. Without the high sound, the urgency dropped.
McComb and colleagues, University of Sussex, 2009How low a cat purrs
House cats purr at about 26 Hz. A 14-year-old cat measured 22.6 Hz, and four cats averaged between 21 and 27 Hz. Only one to four cats were measured each time, so the numbers are a guide.
Sissom and colleagues; Eklund and colleagues, 1991-2011Roaring or purring is not simply down to one bone
An old rule said cats with a rigid hyoid bone purr and cats with a flexible one roar. A study of the throats of lion, tiger, jaguar, cheetah and house cat found no clear link. Whether big cats truly purr is still not settled.
Weissengruber and colleagues; Peters, 2002
Story or true?
A purring cat is always a happy cat.
No. Cats purr when content, but also when hungry, stressed, afraid, in pain or ill. Look at the body and the situation.
Purring heals bones and wounds, so a purring cat will mend itself.
Not proven. A 2001 study saw that the purr matches a vibration used in bone therapy. But nobody has shown that purring makes a cat better. An injured cat still needs a vet.
Big cats never purr.
Cheetahs, cougars and lynx do purr. Lions, tigers, leopards and jaguars roar and make at most short purr-like sounds on the out-breath. Researchers disagree on whether those count as purring.
A purring cat is showing dominance.
No, nothing in the research points to that. Cats purr to keep in touch, to ask for something or to calm down. A purr rather says: I mean no harm.
Did you know?
- 25 Hz
A cat purrs lower than any human voice: measured house cats were between 21 and 27 Hz.
- In and out
A cat purrs on both the in-breath and the out-breath, so you hear no gaps in the sound.
- Hidden cry
A request purr has a cry like a baby's tucked inside. Even people without a cat find it urgent.
- Two days old
Kittens can purr from about two days old, while they still cannot see or hear.
- 40 metres
You can hear a purring cheetah outdoors from more than 40 metres away. Its purr is about as low as a house cat's.
- Genets
Genets, civets and their relatives purr too. They are distant cousins of the cats.
Kittens and older cats
- Kitten
Kittens purr in their first days, while suckling from their mother, and the mother purrs back. It takes a few days of practice before it sounds like an adult purr.
- Older cat
Older cats sometimes purr less or more softly, as purring can tire them. Has an older cat stopped purring? Then watch its moving, eating and comfort, and ask the vet at the next check-up, or sooner if more has changed.
Frequently asked questions
Why does my cat purr when he sees me?
It is a greeting and a way to ask for contact or food. Some cats start purring as soon as you walk in, before any petting. One study found that cats purr more after a longer time apart.
Do cats purr when they're happy?
Usually, yes: the most common reason is that a cat feels relaxed and safe. But cats also purr when hungry, stressed, afraid, in pain or ill. So look at its body and the situation too.
What does it mean when a cat purrs on you?
It feels safe and warm with you and keeps in touch. Often it kneads as well. Sometimes it is also a quiet request for attention.
Why do cats purr when they sleep?
Usually because it is content and resting. Is its breathing easy and does it act normally when it wakes up? Then all is well. If it breathes fast or hard, call the vet.
Why does my cat purr so loud, or louder than other cats?
Some cats simply purr louder than others: how loud a cat purrs differs from cat to cat. It also sounds louder when it is close to your ear or on your chest. A loud purr by itself says nothing about happiness or pain. Only pay attention if it gets clearly louder than normal and other things change too, such as hiding or eating less.
Why does my cat purr all the time?
Some cats purr a lot and others hardly ever, even two cats in one home. For your cat, lots of purring may simply be normal. Is the constant purring new, or does it hide, eat less or seem less active? Then call the vet.
Why does my cat not purr?
Many healthy cats purr very softly or never, and show they like you in other ways. If a cat that always purred stops, it may be stressed, in pain (a sore throat hurts when purring) or getting older. Does it also eat less, hide or rest more? Then see the vet.
Does a cat choose to purr or does it happen by itself?
Nobody knows for sure yet. The voice box can make the sound by itself, but in a living cat the brain switches the purr on and off. Whether a cat chooses to purr has not been worked out yet.
Is a purr called spinnen, knorren or ronken in Dutch?
In Dutch the usual word for a cat's purr is spinnen. Many people also say knorren or ronken for the same low rumble. It is all the same sound.
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