How much chocolate is dangerous for a dog?

The danger depends on three things, the dog's weight, the type of chocolate and the amount, and it can be worked out in a minute. Here are the thresholds, the numbers for common chocolates and what to do next.

Sep 14, 2026 · By Calcelate Team

Chocolate is poisonous to dogs because of theobromine, a stimulant related to caffeine that dogs clear from the body very slowly. A dose that would barely register in a person keeps circulating in a dog for the best part of a day. Whether a given snack is a shrug or an emergency comes down to three numbers: how heavy the dog is, how much theobromine the chocolate contained, and therefore how many milligrams per kilogram of body weight it got.

The thresholds

Veterinary toxicology sources such as the Merck Veterinary Manual put the effects on a scale by dose:

Signs appear 6 to 12 hours after eating and can last for days, because the half-life of theobromine in dogs is around 17 hours. A dog that looks fine an hour later is not in the clear yet.

Why the type of chocolate matters more than the amount

The theobromine content varies by more than a thousandfold between chocolates, so “my dog ate a bar” tells a vet almost nothing until they know which bar.

• White chocolate has almost none, about 0.01 mg per gram. It is a fat and sugar problem, not a poisoning problem.
• Milk chocolate has roughly 2 mg per gram. A 100 g bar holds around 200 mg.
• Dark chocolate at 45–60% cocoa has about 5 mg per gram; 70–85% bars about 8 mg per gram.
• Baker’s or unsweetened chocolate is about 14 mg per gram, seven times milk chocolate.
• Cocoa powder is the worst at around 20 mg per gram. A few spoonfuls can be a serious dose for a small dog.
• Cocoa bean mulch used in gardens is about as strong as dark chocolate and smells appealing to dogs.

Put those together with weight and the picture changes fast. A 30 kg Labrador that eats a 100 g milk chocolate bar gets about 7 mg/kg: unpleasant, probably some vomiting, rarely dangerous. A 5 kg terrier that eats the same bar gets 40 mg/kg, which is the serious-toxicity range. The same terrier with 50 g of dark 70% chocolate is at 80 mg/kg and needs an emergency vet now.

The dog chocolate toxicity calculator does this arithmetic for you: enter the weight, pick the chocolate type and the amount, and it gives the dose in mg/kg with the severity band and the next step. If the result crosses into the danger zone, it also shows the animal poison lines for your country.

What to do right now

1. Work out the dose before you call, or at least have the wrapper in your hand. The vet’s first questions will be the dog’s weight, the type of chocolate and how much is missing. “Most of a family bar of dark” is a usable answer; “some chocolate” is not.
2. Call a vet or an animal poison line if the dose is above about 20 mg/kg, or if you cannot work it out. The ASPCA Animal Poison Control Center and the Pet Poison Helpline in North America, and Animal PoisonLine in the UK, take calls around the clock for a fee. Your regular vet may refer you to an emergency clinic outside hours.
3. Do not induce vomiting at home unless a vet tells you to and tells you how. It can be the right move within the first hour or two, but hydrogen peroxide in the wrong amount or in a dog that is already unsteady causes its own injuries. At a clinic it is done with a controlled drug, followed by activated charcoal to stop further absorption.
4. Watch for signs for at least 24 hours if the dose was low: vomiting, restlessness, panting, a fast heartbeat, tremors. Any of these after a known chocolate dose is a reason to go in.

Two common mistakes

Guessing the weight. People round their dog up. A dog weighed at 4.2 kg on the last vet visit is not “about 5 kg” for this purpose; the difference moves a borderline case across a threshold. If in doubt, weigh the dog on a bathroom scale (you, then you holding the dog).

Forgetting the second helping. Dogs rarely stop at one item. Check whether the wrapper, the box and the shopping bag are all accounted for, and whether the chocolate had nuts, raisins or xylitol-sweetened filling, each of which is a separate poisoning with its own advice.

Chocolate poisoning is one of the most common calls to animal poison lines and one of the most treatable when it is caught early. The maths takes a minute; do it first, then pick up the phone.