Chocolate contains methylxanthines (theobromine and caffeine). The calculator multiplies the amount eaten by the methylxanthine content of that chocolate type, then divides by your dog’s weight to get a dose in mg per kg. It compares that dose with the levels the Merck Veterinary Manual associates with clinical signs:
Merck notes that severe signs and death can occur at much lower doses and that susceptibility varies, so treat any chocolate ingestion as a reason to call your vet.
| Type | mg per gram | mg per ounce |
|---|---|---|
| Cocoa powder | 28.5 | 807 |
| Unsweetened (baker’s) chocolate | 15.5 | 440 |
| Cocoa bean hulls | 9 | 255 |
| Semisweet and sweet dark chocolate | 5.3–5.6 | 150–160 |
| Milk chocolate | 2.3 | 64 |
| White chocolate | 0.04 | 1.1 |
The calculator uses the higher value (5.6 mg/g) for dark chocolate. Some cocoa bean hulls have had methylxanthines removed. Products vary, so real content can differ.
According to the Merck Veterinary Manual, mild signs such as vomiting, diarrhea and excess thirst are seen at about 20 mg of methylxanthines per kg of body weight, heart effects at 40–50 mg/kg, and seizures at 60 mg/kg or more. Severe signs can occur at lower doses, and dogs vary.
Cocoa powder and unsweetened baker’s chocolate contain the most methylxanthines, followed by dark chocolate and milk chocolate. White chocolate contains a negligible amount.
Merck says clinical signs usually begin 6 to 12 hours after ingestion, and in severe cases can last up to 72 hours.
Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 right away, even if your dog seems fine. Have your dog’s weight, the type of chocolate and the amount ready.
Last checked: November 11, 2026. Estimate only, not veterinary advice.
