Unlike meowing, which comes from the vocal cords, purring is produced by the rapid vibration of the laryngeal muscles and the hyoid bone in the throat. Cats can purr both when inhaling and exhaling — a unique ability shared by only a few animals. The frequency of a cat’s purr (usually 25–150 Hz) is remarkably consistent across breeds and even across wild felids like cheetahs and pumas.

This specific frequency range is no accident. Research shows that 25–50 Hz vibrations promote bone growth and healing, while 100–150 Hz can relieve pain and reduce swelling. Nature seems to have built a built-in healing mechanism into the purr.

The classic “happy purr” happens during petting, feeding, or nursing. Mother cats purr to reassure kittens, and kittens purr back to signal they’re getting milk. Adult cats purr to strengthen their bond with you.

Cats purr when they’re anxious, at the vet, or in a new environment. The vibration releases endorphins that calm them down — like a built-in stress-relief tool.

Injured or sick cats purr more. The frequency stimulates tissue repair, increases blood flow, and releases natural painkillers. Veterinarians often hear hospitalized cats purring even when they’re in obvious discomfort.

A hungry cat uses a special “solicitation purr” — a mix of purr and meow that’s hard for humans to ignore. It’s evolution’s way of getting your attention at 5 a.m.

Many cats purr softly in their final hours. It may be a way to self-soothe or say goodbye.

For cats:

• Reduces stress hormones
• Promotes bone density and healing
• Lowers pain perception
• Improves breathing and oxygenation

For humans:

• Lowers blood pressure and heart rate
• Reduces anxiety and cortisol
• Improves mood through oxytocin release
• May even help with chronic pain when you pet a purring cat

One study found that people who own cats have a significantly lower risk of heart attack — partly because of the calming effect of purring.

Not all purrs sound the same. Learn to read your cat’s purr:

• Soft, steady purr — pure contentment
• Louder, rhythmic purr with a “meow” mixed in — the solicitation purr (usually at mealtime)
• Quiet, almost vibrating purr while eyes are half-closed — deep relaxation or self-soothing
• Short, broken purr while breathing heavily — possible pain or respiratory issue

Purring is usually positive, but sometimes it’s a sign something is wrong. Contact your vet if your cat is purring while also showing:

• Difficulty breathing or rapid breathing
• Lethargy or hiding more than usual
• Loss of appetite
• Limping or reluctance to jump
• Excessive drooling or vocalizing

A cat purring while in obvious pain or distress needs immediate attention.