Dog Chocolate Toxicity Calculator: My Dog Ate Chocolate, How Much Is Dangerous?

Chocolate is poisonous to dogs because of theobromine, a stimulant they clear far more slowly than we do. How dangerous a single incident is comes down to three things: your dog's weight, the type of chocolate, and how much it ate. This calculator estimates the theobromine dose in milligrams per kilogram and shows which risk band that falls into. It is a guide to help you judge urgency, not a substitute for a vet.

If your dog has eaten chocolate, phone your vet or an out-of-hours vet now. In the UK you can also ring the Animal PoisonLine on 01202 509000 (a paid service run by the Veterinary Poisons Information Service). Do not wait for symptoms to appear, and do not try to make your dog sick unless a vet tells you to.

How this works: we multiply the weight of chocolate eaten by a typical theobromine content for that type, then divide by your dog's bodyweight to get a dose in milligrams per kilogram. Vets generally treat under 20 mg/kg as a low risk of anything worse than an upset stomach, 20 to 40 mg/kg as likely to cause vomiting, diarrhoea, restlessness and a fast heart rate, 40 to 60 mg/kg as a serious dose with heart effects, and above 60 mg/kg as severe, with a real risk of tremors and seizures. Doses above roughly 100 mg/kg can be fatal. These are broad thresholds and every dog reacts differently, so a low reading here still does not mean do nothing.

The theobromine figures are averages, and real bars vary a lot, so treat the number as an estimate. If you are unsure how much your dog ate, assume the worst case. Puppies, elderly dogs and dogs with a heart condition are more vulnerable, and other ingredients such as raisins in some chocolates carry their own danger. When in doubt, ring your vet and tell them your dog's weight, the type of chocolate and roughly how much, ideally with the wrapper to hand.