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Dog grape & raisin toxicity calculator
Your dog ate grapes or raisins? Enter their weight and how many they ate to compare with the veterinary risk level.
How the amount compares with the risk level, and what to do next, will show here.
There is no known safe amount of grapes or raisins for dogs. This tool helps you judge urgency; it does not replace a vet. Last reviewed October 7, 2026.
Why grapes and raisins are dangerous for dogs
Grapes, raisins and other dried grapes such as sultanas and currants can cause sudden kidney failure in dogs. The Merck Veterinary Manual names tartaric acid, which these fruits contain in high amounts, as the toxic principle. Tamarinds, which are also rich in tartaric acid, cause the same problem.
The amount of tartaric acid varies a lot from fruit to fruit. That is why some dogs eat grapes without trouble and others get seriously ill after a few, and why vets don't treat any amount as safe.
How the calculator works
The Merck Veterinary Manual says that more than one grape or raisin per 4.5 kg (10 lb) of body weight may contain enough tartaric acid to pose a risk. The calculator divides your dog's weight by 4.5 kg to find that level, then compares it with the number eaten.
| Dog's weight | Risk level (grapes or raisins) |
|---|---|
| 10 lb (4.5 kg) | more than 1 |
| 20 lb (9 kg) | more than 2 |
| 40 lb (18 kg) | more than 4 |
| 60 lb (27 kg) | more than 6 |
| 80 lb (36 kg) | more than 8 |
What happens and when
- 6 to 12 hours: most affected dogs start vomiting or have diarrhea.
- 24 to 72 hours: kidney failure can develop, with the dog making little or no urine.
Vets usually try to get the fruit out of the stomach as soon as possible and then give IV fluids for at least 48 hours while checking kidney values. Treatment works best when it starts early, so call before signs appear.
Don't wait for symptoms. If your dog ate grapes or raisins, call your vet or a pet poison line straight away, even if the number is below the risk level. Don't try to make your dog vomit at home unless a vet tells you to.
Questions people ask
How many grapes can kill a dog?
There is no fixed number. The Merck Veterinary Manual gives a risk level of more than one grape or raisin per 10 lb (4.5 kg) of body weight, but because tartaric acid content varies, some dogs get sick from fewer. Treat any amount as a reason to call your vet.
My dog ate one grape. Will it be okay?
Many dogs are fine after one grape, especially larger dogs, but no amount is known to be safe. Call your vet for advice, and watch for vomiting, diarrhea, tiredness or less urine over the next few days.
Are raisins worse than grapes?
Raisins are dried grapes, so they are smaller and easier for a dog to eat in large numbers. The Merck risk level is given per fruit, for grapes and raisins alike.
How long after eating grapes will a dog get sick?
Vomiting or diarrhea usually starts within 6 to 12 hours. Kidney failure can follow within 24 to 72 hours.
Are grape products like juice, jam or wine dangerous?
They are made from grapes and may contain tartaric acid, so ask your vet if your dog had any. Wine also contains alcohol, which is toxic to dogs on its own.