Emergency Tool
Chocolate toxicity calculator for cats
Work out whether the chocolate your cat ate is a toxic dose. Based on UK veterinary theobromine thresholds for cats — roughly 20mg/kg for concerning signs, 40–60mg/kg for severe toxicity.
While you wait for your vet to answer
If your cat has eaten chocolate, call your vet now. This calculator is a quick way to understand severity while you're waiting — not a substitute for professional advice.
In the UK: your vet first, then the Animal PoisonLine on 01202 509000 (24/7, charges apply).
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Most adult UK domestic cats are 3.5–5.5 kg. Kittens are much smaller — toxicity thresholds scale with weight.
If unsure, check the wrapper. For unknown types, pick the closest match.
A typical chocolate square is ~5g. A freddo is ~18g. A 100g bar is a full bar. A teaspoon of cocoa powder is ~2g.
How this calculator works
Chocolate contains two stimulants — theobromine and caffeine — that cats metabolise poorly. The calculator estimates theobromine dose per kilogram of body weight using published values for each chocolate type:
- Under 9 mg/kg — likely below symptomatic threshold, but watch closely for 24 hours.
- 9–20 mg/kg — mild signs possible (vomiting, restlessness, thirst). Vet call recommended.
- 20–40 mg/kg — moderate toxicity likely. Vet visit needed.
- 40–60 mg/kg — significant toxicity — heart rate, tremors. Emergency.
- Over 60 mg/kg — severe, potentially fatal without aggressive treatment. Emergency.
Cats are generally more sensitive than dogs to theobromine and also metabolise it more slowly (half-life ~17 hours). Symptoms can persist 24–36 hours even with treatment.
Signs of chocolate toxicity in cats
2–4 hours
Vomiting, diarrhoea, increased thirst, restlessness.
6–12 hours
Rapid heart rate, tremors, elevated temperature, rapid breathing.
12–36 hours
Seizures, collapse, cardiac arrhythmias in severe cases.