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Dog chocolate toxicity calculator
Enter what your dog ate and how much it weighs to see how serious the dose may be.
How the calculator works
Chocolate harms dogs because of two stimulants in cocoa, theobromine and caffeine, together called methylxanthines. Vets judge the risk by the dose: milligrams of methylxanthines per kilogram of the dog's body weight. The darker the chocolate and the smaller the dog, the higher the dose.
The calculator multiplies the amount eaten by the methylxanthine content of that kind of chocolate, then divides by your dog's weight. The contents and dose levels come from the Merck Veterinary Manual. For a bar with a cacao percentage on the label, it uses Merck's rule: about 15.5 mg per gram (the figure for unsweetened chocolate), times the cacao percentage. For a dark bar with no percentage, it assumes 85% to be on the safe side.
Dose levels
From the Merck Veterinary Manual. Individual dogs vary.
| Dose (mg per kg) | What can happen |
|---|---|
| 20 | Mild signs: vomiting, diarrhea, drinking a lot |
| 40 to 50 | Effects on the heart, such as a racing or irregular heartbeat |
| 60 and up | Seizures |
| 100 to 200 | The range where half of dogs would die (the LD50) |
How much chocolate is a problem?
Ounces of each chocolate that reach 20 mg per kg, where mild signs usually start, for dogs of 10, 25, 50 and 75 lb. One ounce is about 28 grams.
| Chocolate | 10 lb | 25 lb | 50 lb | 75 lb |
|---|---|---|---|---|
| Milk chocolate64 mg per oz | 1.4 | 3.5 | 7.0 | 10 |
| Semisweet chocolate, chocolate chips160 mg per oz | 0.5 | 1.4 | 2.8 | 4.2 |
| Cocoa bean hulls (garden mulch)255 mg per oz | 0.3 | 0.8 | 1.7 | 2.6 |
| Dark chocolate, 70% cacao308 mg per oz | 0.2 | 0.7 | 1.4 | 2.2 |
| Unsweetened baking chocolate440 mg per oz | 0.2 | 0.5 | 1.0 | 1.5 |
| Cocoa powder807 mg per oz | 0.1 | 0.2 | 0.5 | 0.8 |
Contents from the Merck Veterinary Manual (semisweet at the top of its 150 to 160 mg range). The 70% bar uses Merck’s 15.5 mg per gram rule. Real products vary.
Signs to watch for
Signs can start anywhere from about 2 to 12 hours after eating, sometimes later, so a dog that seems fine at first can still become ill. They can last up to three days in severe cases.
- Early: vomiting, diarrhea, drinking a lot, a swollen belly, restlessness, panting.
- Getting worse: hyperactivity, peeing a lot, wobbly walking, stiffness, tremors, a racing heart.
- Severe: seizures, an abnormal heart rhythm, overheating, blue or gray gums, collapse, coma.
What to do now
- Work out what was eaten, how much, and when. Keep the wrapper: the cacao percentage and weight help.
- Call your vet, an emergency vet, or a pet poison line right away, even if your dog seems fine. Making a dog vomit works best within about 2 hours of eating, so don't wait for signs to appear.
- Don't try to make your dog vomit unless a vet tells you to.
- If your dog is trembling, collapsing or having a seizure, go straight to the nearest emergency vet.
This calculator is for dogs. If a cat has eaten chocolate, call your vet or a poison line.
Common questions
How much chocolate can kill a dog?
Merck gives 100 to 200 mg per kg as the dose that kills half of dogs (the LD50). For a 20 lb dog that's roughly 14 to 28 oz of milk chocolate, but only about 2 to 4 oz of unsweetened baking chocolate. Dogs can become seriously ill at well under half of that, so don't wait for a dangerous-looking number before calling a vet.
Is milk chocolate dangerous for dogs?
Less than dark chocolate, but yes in larger amounts. Milk chocolate has about 64 mg of methylxanthines per ounce, so a 10 lb dog reaches the mild-signs level at about 1.4 oz.
Is white chocolate dangerous for dogs?
It contains almost no theobromine or caffeine (about 1 mg per ounce), so poisoning from white chocolate is very unlikely. It's still very fatty, and the Merck Veterinary Manual notes that the fat in chocolate can trigger pancreatitis in some dogs, so call your vet if your dog ate a lot or seems unwell.
How long after eating chocolate will a dog get sick?
Signs can start anywhere from about 2 to 12 hours after eating, sometimes later, so a dog that seems fine at first can still become ill. They can last up to three days in severe cases. Vets advise calling before signs appear rather than waiting for them.
What about brownies, cake or cookies?
They vary too much to list. Check the recipe or label for how much chocolate or cocoa went in, and how much of the batch your dog ate. Cocoa powder and baking chocolate are the strongest, so a small amount of a rich brownie can matter for a small dog. Also tell your vet about other ingredients: raisins, macadamia nuts and the sweetener xylitol (in some sugar-free treats) are dangerous to dogs too.
Sources: Hayes C, “Chocolate Toxicosis in Animals”, Merck Veterinary Manual (full review September 2024, updated February 2026). Washington State University College of Veterinary Medicine, “Chocolate toxicity in dogs” (2026). This calculator gives an estimate to help you judge urgency. It is not a diagnosis or veterinary advice.