Grape and Raisin Toxicity Calculator for Dogs
Check the dose from grapes or raisins by body weight. Any amount can be dangerous, so this shows where the reported toxic doses begin rather than offering a safe limit.
Guess high if you are not sure. Count the ones missing from the bunch or packet.
One grape weighs roughly 5 g.
Any amount is a concern
2.50 g per kg body weight
Vomiting is usually the first sign, within 24 hours. Kidney injury can follow 24 to 72 hours later, sometimes without warning.
Call a vet or a poison control line now, whatever the amount. There is no dose considered safe, and treatment is far more effective before signs appear.
- Amount eaten
- 50.0 g
- Lowest reported toxic dose
- 19.6 g/kg
- Percentage of that dose
- 13%
Treat that percentage with caution. It compares against the lowest dose ever reported to cause harm, not against a safe limit. Dogs have developed kidney failure after a single grape, and others have eaten far more with no effect at all. Susceptibility appears to be individual and cannot be predicted.
How this is calculated
The calculation itself is simple. The interpretation is the difficult part, because grape toxicosis has no reliable dose-response relationship.
grams eaten = units × grams per unit
dose (g/kg) = grams eaten ÷ body weight in kg Reported toxic doses
| Form | Typical weight | Lowest reported toxic dose |
|---|---|---|
| Fresh grapes | 5 g per grape | 19.6 g/kg |
| Raisins or sultanas | 0.5 g per raisin | 2.8 g/kg |
| Dried currants | 0.4 g per currant | 2.8 g/kg |
| Grape juice | 30 g per tablespoon | 19.6 g/kg |
Why there is no safe threshold
For most toxins, a dose below the threshold means no effect. Grapes do not behave that way. Published case reports include dogs developing fatal kidney failure from very small amounts, alongside dogs in the same household eating far more and remaining well.
The tartaric acid hypothesis explains this. Tartaric acid content varies enormously between grape varieties, ripeness and growing conditions, so two grapes of the same size can carry very different doses. Individual differences in how dogs handle it likely add to the spread.
Sources
- Merck Veterinary Manual. Grape, Raisin, and Tamarind (Vitis spp, Tamarindus spp) Toxicosis in Dogs.
- Wegenast CS, Meadows ID, Anderson RE, Southard T, González Barrientos CR, Wismer TA. Acute kidney injury in dogs following ingestion of cream of tartar and tamarinds and the connection to tartaric acid as the proposed toxic principle in grapes and raisins. J Vet Emerg Crit Care. 2022;32(6):812–816.
- ASPCA Animal Poison Control Center. People foods to avoid feeding your pets.
The hidden sources
Most grape incidents are not a dog eating grapes off a bunch. They are dried fruit in baking: fruit cake, cinnamon raisin bread, oatmeal raisin cookies, scones, granola bars, trail mix and cereal. The fruit is small, dark and easy to forget about when you list what the dog got into.
When you call the vet, describe the whole food rather than just the fruit. A mince pie is a raisin dose and a fat dose at once.
Timing matters more than the number
Decontamination within a couple of hours is straightforward and effective. Treating established acute kidney injury is neither. That asymmetry is the reason the advice here is the same at every dose: call now, rather than watching and waiting.
Common questions
How many grapes are toxic to a dog?
There is no known safe number. Kidney failure has been reported after a single grape in some dogs, while others have eaten large quantities with no ill effect. The lowest doses associated with harm are about 19.6 g/kg for grapes and 2.8 g/kg for raisins, but those are lowest reported doses, not thresholds of safety.
My dog ate one grape. Should I worry?
Call your vet or a poison control line. Given that susceptibility appears individual and unpredictable, most veterinary toxicologists advise decontamination for any known ingestion, especially in a small dog. It is a cheap, quick intervention compared with treating established kidney failure.
Why are grapes toxic to dogs?
Tartaric acid and its potassium salt are the leading explanation, identified in 2021. It fits the evidence well: it explains why cream of tartar and tamarind cause similar signs, and why the toxic dose varies so much, since tartaric acid content varies hugely between grape varieties and growing conditions.
Are raisins worse than grapes?
Yes, by weight. Drying removes the water and concentrates everything else, so the reported toxic dose for raisins is roughly seven times lower per gram. A handful of raisins is a far bigger dose than a handful of grapes.
What are the symptoms of grape poisoning?
Vomiting is usually first, often within a few hours. Then lethargy, diarrhea, loss of appetite and abdominal pain. Acute kidney injury develops over 24 to 72 hours, and by the time urine production drops the damage is well established.
What will the vet do?
If the ingestion was recent, induce vomiting and give activated charcoal. Then intravenous fluids for 48 to 72 hours to protect the kidneys, with blood tests to monitor kidney values. Started early, the outlook is good; started after kidney failure develops, it is much worse.
What about currants, sultanas and grape juice?
All the same concern. Watch particularly for baked goods: fruit cake, cinnamon raisin bread, oatmeal raisin cookies and granola bars are common accidental sources, and the fruit is easy to overlook.