What this calculator does
Important: acetaminophen (paracetamol, sold as Tylenol) is extremely toxic to cats and should never be given to them. Cats lack adequate amounts of the liver enzyme glucuronyl transferase needed to safely metabolize the drug, so even a single regular tablet can be lethal. This tool estimates the dose a cat ingested, in milligrams per kilogram of body weight, and compares it to the commonly cited feline toxic threshold of about 10 mg/kg.
How to use it
Enter your cat's weight (in kilograms or pounds) and the total amount of acetaminophen ingested in milligrams. If you know the number and type of tablets, multiply: a Regular Strength Tylenol tablet contains 325 mg and Extra Strength contains 500 mg. The calculator divides the total milligrams by body weight and flags whether the dose crosses the toxic threshold.
The formula explained
The math is a simple per-weight dose:
$$\text{Dose}_{mg/kg} = \dfrac{\text{mg ingested}}{\text{weight}_{kg}}$$Pounds are converted using \(1\ \text{lb} = 0.4536\ \text{kg}\). Doses above ~10 mg/kg are considered potentially toxic in cats, and signs of severe poisoning are common well above this level:
$$\text{Toxic if } \text{Dose}_{mg/kg} > 10$$There is no truly "safe" dose for a cat.
Worked example
A 4.5 kg cat swallows one Extra Strength tablet (500 mg).
$$\text{Dose} = \frac{500}{4.5} = 111.1\ \text{mg/kg}$$— far above the 10 mg/kg threshold and a life-threatening emergency requiring immediate veterinary care.
FAQ
What are the symptoms of acetaminophen poisoning in cats? Brown/blue gums (methemoglobinemia), difficulty breathing, facial or paw swelling, drooling, vomiting, lethargy, and dark urine. Symptoms can appear within hours.
How much Tylenol is dangerous for a cat? Any amount can be dangerous. Doses above roughly 10 mg/kg are considered toxic, but even small ingestions justify an emergency vet visit.
What should I do right now? Do not wait for symptoms. Call your veterinarian, an emergency animal hospital, or a pet poison control hotline immediately. Bring the packaging so they know the exact strength and amount.
