My dog ate chocolate: how much is dangerous?
Mild signs can start at about 20 mg of theobromine and caffeine per kg of body weight, heart effects at 40 to 50 mg/kg and seizures from 60 mg/kg. Dark and baking chocolate are far more dangerous than milk chocolate: 1 oz of baking chocolate has about 7 times the dose of 1 oz of milk chocolate.
Free, no sign-up · Reviewed October 2026 · How it works
Type of chocolate
Check the wrapper for the weight. For reference, a standard milk chocolate bar is often 1.55 oz (43 g) and a large bar 100 g (3.5 oz).
Estimated dose
11.3mg/kg
Unlikely to cause signs
About 113 mg of theobromine and caffeine for a 10.0 kg dog.
- Unlikely to cause signsunder 20 mg/kg
- Mild signs: vomiting, diarrhoea, thirst20+ mg/kg
- Heart effects: racing heart, restlessness40+ mg/kg
- Severe: tremors and seizures possible60+ mg/kg
Below the level where signs usually start, but dogs vary and the fat and sugar can still upset the stomach. Call your vet if your dog is a puppy, has a heart condition, or shows any vomiting, restlessness or a racing heart. Signs can take 6 to 12 hours to appear.
For information only, not a diagnosis or a substitute for your vet. If your pet seems unwell or you're worried, call your vet.
How this tool works
Chocolate is dangerous because of methylxanthines, mainly theobromine with some caffeine. The calculator multiplies the amount eaten by the methylxanthine content of that type of chocolate, from the Merck Veterinary Manual: about 64 mg per oz for milk chocolate, 150 to 160 for dark, 440 for baking chocolate and 807 for cocoa powder.
It divides that by your dog's weight to give a dose in mg/kg and compares it with the levels at which signs have been seen: 20 mg/kg for mild signs, 40 to 50 for heart effects and 60 or more for seizures.
Dogs vary, and signs can take 6 to 12 hours to appear, so if you're unsure, call your vet or the ASPCA Animal Poison Control Center on (888) 426-4435 straight away rather than waiting.
Questions.
How much chocolate can kill a dog?
Severe poisoning and death can happen at much lower doses than the 100 to 200 mg/kg reported as lethal in studies. The Merck Veterinary Manual notes that about 1 oz of milk chocolate per lb of body weight is potentially lethal; dark and baking chocolate are dangerous in much smaller amounts.
My dog ate chocolate but seems fine. What should I do?
Work out the dose with this calculator and call your vet if it's 20 mg/kg or more, even if your dog seems fine. Signs often start 6 to 12 hours later, and treatment works best early.
Is white chocolate dangerous for dogs?
It contains almost no theobromine, so poisoning is very unlikely, but the fat and sugar can still cause vomiting, diarrhoea and, in some dogs, pancreatitis.
How long does chocolate poisoning last?
Signs usually start within 6 to 12 hours and can last up to 72 hours, because dogs clear theobromine slowly.
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