The dose depends on body weight, not grams eaten
Chocolate is toxic to cats because of theobromine (with some caffeine). Cats break it down slowly, so risk is measured as milligrams of theobromine per kilogram of the cat's weight — a bite that is harmless to a large cat can affect a small one.
This is an estimate for context only. It is not veterinary advice. If your cat has eaten chocolate, contact your vet or a pet poison control line without waiting.
Theobromine by chocolate type
The same weight of chocolate carries very different doses. This is why the type matters more than the amount at first glance.
| Type | Theobromine | Risk |
|---|---|---|
| White chocolate | ~0 mg/g | Negligible (theobromine); still fatty and sugary |
| Milk chocolate | 1.5–3 mg/g | Low in small amounts |
| Dark chocolate (50%) | 5–10 mg/g | Moderate |
| Dark chocolate (70%+) | 12–26 mg/g | High |
| Baking chocolate / cocoa | 23–28 mg/g | Very high |
A 4 kg cat reaches the ~20 mg/kg signs threshold (about 80 mg theobromine) with roughly 30 g of milk chocolate — or only about 5 g of baking chocolate.
Same 10 grams, very different dose
Ten grams of baking chocolate delivers over ten times the theobromine of ten grams of milk chocolate. For a 4 kg cat, the ~80 mg signs threshold is crossed by the dark and baking bars but not the milk one.
Rough thresholds and what to watch for
- ~20 mg/kg — first signs possible: restlessness, vomiting, increased thirst.
- ~40–50 mg/kg — cardiac effects: fast or irregular heartbeat, tremors.
- ~100+ mg/kg — serious risk: seizures; a life-threatening dose approaches ~300 mg/kg.
- Timing — signs typically begin 6 to 12 hours after eating and can persist for up to 72 hours. There is no home antidote; treatment is supportive and best started early.
Common questions
My cat ate chocolate — what should I do?
Call your vet or a pet poison line right away with the cat's weight, the type of chocolate and roughly how much it ate. Early treatment is far more effective than waiting for symptoms. This tool estimates the dose but is not veterinary advice.
How much chocolate is toxic to a cat?
Toxicity is set by theobromine per body weight, not by the raw grams. Signs typically start near 20 mg of theobromine per kg of cat. For a 4 kg (9 lb) cat that is about 80 mg total, which is roughly 30 g of milk chocolate or as little as 5 g of baking chocolate.
Is dark chocolate worse than milk chocolate for cats?
Yes, by a wide margin. Dark chocolate holds several times more theobromine per gram than milk chocolate, and baking chocolate and cocoa powder are the most concentrated of all. White chocolate has essentially none.
How long until symptoms appear?
Usually 6 to 12 hours after eating, and signs can last 24 to 72 hours because cats clear theobromine slowly. Do not wait for symptoms before calling a vet.
