Grape & Raisin Toxicity Calculator for Dogs
Compare what your dog ate against the smallest amounts ever documented to cause kidney injury.
Last reviewed July 2026 · Free · Nothing you enter is stored
There is no dose of grapes or raisins that is known to be safe for dogs.
Call your veterinarian, the ASPCA Animal Poison Control Center at (888) 426-4435, or the
Pet Poison Helpline at (855) 764-7661. Decontamination in the first two hours is the single
most effective thing that can be done, and it stops being an option once symptoms start.
Why this calculator can't tell you that your dog is fine
Every other toxicity calculator on this site works the same way: a known amount of a known compound, a published dose-response curve, and an answer. Grapes break that model. There is no reliable dose-response relationship. Dogs have died after eating a small handful, and dogs have eaten an entire bunch with no ill effect at all, and nothing about the animals — breed, age, sex, size, prior exposure — predicts which group a given dog falls into.
What this tool gives you instead is a comparison. It converts what was eaten into grams per kilogram of body weight and sets that against the lowest doses ever documented to cause acute kidney injury: 19.6 g/kg for fresh grapes and 2.8 g/kg for dried fruit. Being below those numbers is not a clean bill of health. Being above them means you are past the point where poisoning has already been observed in a real dog.
The tartaric acid discovery
The mechanism was a genuine mystery from the first case reports in the late 1980s until 2021. Pesticides were ruled out. Heavy metals were ruled out. Mycotoxins on the fruit skin were the leading theory for years and never held up.
The break came from an unrelated poisoning. A dog ate homemade play dough and developed the identical pattern of kidney injury, and the recipe's distinguishing ingredient was cream of tartar — potassium bitartrate. Grapes happen to be one of the very few foods with a high natural tartaric acid content; it is the acid the wine industry has to manage in every vintage. Dogs appear to lack an efficient route to clear it. The ASPCA team published the hypothesis in the Journal of the American Veterinary Medical Association in 2021 and it has held up since.
This also explains the erratic dose-response. Tartaric acid content in grapes swings widely by cultivar, growing conditions, and ripeness at harvest — so two visually identical grapes can carry substantially different loads of the toxic agent. The dog is not the variable. The grape is.
Documented toxic doses
| Form | Lowest documented toxic dose | What that looks like |
|---|
| Fresh grapes | 19.6 g/kg (0.7 oz/kg) | About 4 grapes for a 10 lb dog; about 18 for a 45 lb dog |
| Raisins, sultanas, currants | 2.8 g/kg (0.11 oz/kg) | About 6 raisins for a 10 lb dog; about 25 for a 45 lb dog |
Lowest documented toxic doses from ASPCA Animal Poison Control Center case series. These are the smallest amounts associated with kidney injury in reported cases, not safety thresholds.
Where dogs actually find them
| Source | Concentration | Notes |
|---|
| Fresh grapes, seedless or seeded | ~5 g each | Colour, variety, and seeds make no difference to the risk. |
| Raisins and sultanas | ~0.5 g each | Ten times more concentrated than grapes by weight. A small box holds 60–90. |
| Dried currants | ~0.35 g each | Often mistaken for the fresh blackcurrant, which is a different plant entirely and not implicated. |
| Raisin bread, hot cross buns, scones | variable | A common Christmas and Easter poisoning, often eaten off a counter. |
| Fruitcake, mince pies, Christmas pudding | very high | Dense with dried vine fruit, and frequently left out for days. |
| Trail mix, granola bars, breakfast cereal | variable | Easy to overlook — check the ingredient panel, not the front of the box. |
| Grape juice and wine | unclear | Reported cases are rare, but juice and must have not been shown safe. Alcohol is its own separate problem. |
| Grape seed extract | not implicated | Supplements made from grape seed have not been linked to kidney injury. |
Baked goods deserve particular attention. Most reported poisonings are not a dog eating grapes off a vine — they are a dog eating a hot cross bun, a slice of fruitcake, or half a box of raisin bran. The fruit is hidden in the product, the quantity is hard to reconstruct after the fact, and the season concentrates the risk: December and Easter are the busiest weeks for these calls.
What treatment looks like
If the ingestion is recent and the dog is asymptomatic, the vet will induce vomiting and give activated charcoal, which does bind here — unlike with xylitol. That alone resolves most cases where the dog arrives early.
Beyond that window, the standard of care is intravenous fluid diuresis for 48 to 72 hours, with kidney values checked at baseline, 24, 48, and 72 hours. Fluids maintain renal perfusion while the insult passes. The prognosis is excellent for dogs treated before their creatinine rises and guarded once it has — dogs that become anuric, meaning they stop producing urine, often need dialysis and many do not survive.
The through-line in every version of this is the same: what changes the outcome is the hour you call, not the number of grapes.
Frequently asked questions
How many grapes are toxic to a dog?
There is no established safe number. The lowest documented toxic dose is about 0.7 oz of grapes per kilogram of body weight — roughly four grapes for a 10 lb dog — but that figure comes from case reports, not from a threshold below which dogs are known to be fine. Some dogs eat a whole bunch without consequence and others develop acute kidney injury after a handful. Treat any deliberate ingestion as worth a phone call.
Are raisins worse than grapes?
Per piece, yes, and by a wide margin. Drying removes most of the water, so a raisin carries roughly the same toxic load as a grape in a tenth of the mass. The lowest documented toxic dose for dried fruit is about 0.11 oz/kg, which for a 20 lb dog is around a dozen raisins. That is why a spilled box of raisins is a more serious event than a dropped grape.
What actually causes grape toxicity in dogs?
For two decades nobody knew. In 2021 a team at the ASPCA Animal Poison Control Center published a case series in JAVMA proposing tartaric acid and its salt potassium bitartrate as the agent, after a dog poisoned by homemade play dough — which contains cream of tartar — produced identical kidney injury. Grapes are unusually high in tartaric acid, dogs appear to lack an efficient pathway to clear it, and tartaric acid content varies enormously with grape variety and ripeness. That variability neatly explains why the dose-response has always looked so erratic.
What are the symptoms of grape poisoning?
Vomiting is usually first, often within six hours, sometimes with recognisable fruit in it. Then lethargy, loss of appetite, diarrhoea, and abdominal tenderness over the next day. Kidney injury shows up 24 to 72 hours in, initially as increased drinking and urination, then decreased urination as the kidneys fail. By the time urine output drops, the damage is already substantial — which is the whole argument for treating early rather than waiting to see.
Are grapes toxic to cats?
Documented cases in cats are very rare, but that most likely reflects the fact that cats do not taste sweetness and rarely eat fruit rather than any proven resistance. Ferrets have been poisoned. If a cat has eaten grapes or raisins, call a poison line rather than assuming immunity.
My dog ate one grape three days ago and seems fine. Should I worry?
If three full days have passed with no vomiting, normal appetite, normal drinking, and normal urination, the acute window has closed. If you have any doubt, a single blood chemistry panel checking creatinine, urea, and SDMA settles it — SDMA in particular picks up kidney damage earlier than the older markers do.
Lowest documented toxic doses are 0.7 oz/kg for fresh grapes and 0.11 oz/kg for raisins, from ASPCA Animal Poison Control case series. No safe dose has ever been established — the reaction is idiosyncratic and some dogs develop acute kidney injury after a handful. Tartaric acid and potassium bitartrate are the suspected agents (Wegenast et al., JAVMA 2021).