The safe amount of grapes for a dog
Zero
grapes and raisins are toxic — no amount is safe
published thresholds: 10–30 g of grapes per kg (APCC) · 3 g of raisins per kg (Morrow 2005)
Can Dogs Eat Grapes?
No. Grapes, raisins, sultanas and Zante currants are toxic to dogs — the answer is zero grams. Unlike the other fruits on this site where the question is “how many grams fit the 10% treat ceiling,” grapes are a toxicology question, not a nutrition question. The toxic principle was unidentified for over 20 years; in 2021, tartaric acid was identified as the likely culprit. The dose that causes kidney failure is unpredictable — some dogs develop acute renal failure after a few grapes, while others eat large amounts with no effect. This page takes the published dose thresholds, the case fatality data, and the treatment timeline, and shows exactly how little it takes by body weight.
The risk threshold calculator
Enter your dog’s weight to see the published toxic thresholds
Body weight: 30 lb = 13.61 kg
Grapes — lower toxic threshold (10 g/kg): 136 g = ~41 grapes
Grapes — upper toxic threshold (30 g/kg): 408 g = ~124 grapes
Raisins — kidney failure threshold (3 g/kg): 41 g = ~2.7 tablespoons
WebMD risk line (1 grape per 10 lb): 3 grapes = ~10 g = 0.73 g/kg
Raisin concentration factor: 4.29× (296 vs 69 kcal/100 g)
How the numbers are built, step by step
The thresholds on this page come from three published sources. Here is the full chain for a 30 lb dog:
Step 2 — Grape lower threshold (APCC): 10 g/kg × 13.61 = 136 g
One Thompson Seedless grape weighs ~3.3 g (USDA) → 136 ÷ 3.3 = ~41 grapes
Step 3 — Grape upper threshold (APCC): 30 g/kg × 13.61 = 408 g → 408 ÷ 3.3 = ~124 grapes
Step 4 — Raisin threshold (Morrow et al. 2005): 3 g/kg × 13.61 = 41 g
Raisin density ~15 g/tablespoon → 41 ÷ 15 = ~2.7 tablespoons
Step 5 — WebMD conservative line: 1 grape per 10 lb → 30 ÷ 10 = 3 grapes = ~10 g = 0.73 g/kg
Step 6 — Raisin concentration: USDA SR Legacy
Grapes (fdcId 174683): 69 kcal/100 g, water 80.54%
Raisins (fdcId 168166): 296 kcal/100 g, water 16.57%
296 ÷ 69 = 4.29× — raisins are 4.29 times as calorie-dense as fresh grapes
Water drops from 80.54% to 16.57% → the toxic principle concentrates by the same factor
Step 7 — Cross-check: 3 g/kg raisins × 4.29 = 12.9 g/kg grape equivalent
This falls inside the APCC grape range (10–30 g/kg) — the two thresholds are consistent
The 2021 tartaric acid finding
For over two decades the toxic principle in grapes was unknown. In 2021, researchers identified tartaric acid (and its salt, potassium bitartrate) as the likely cause — published in Clinician’s Brief (2023, Gray et al.). The key facts:
| What | Value | Source |
|---|---|---|
| Tartaric acid in grapes | 0.35%–1.1% (up to 2%) | Gray 2023, Clinician’s Brief |
| Tartaric acid concentration in raisins | ~4.3× higher than fresh | Inferred from water loss (80.54% → 16.57%) |
| Dogs that cannot tolerate tartaric acid | All breeds, all sizes | Cornell Riney Canine Health Center |
| Why some dogs are unaffected | Unknown — individual sensitivity varies | Sutton et al. 2009; Cornell |
Tartaric acid varies from bunch to bunch and even within a single grape, which explains why two dogs eating the same amount can have vastly different outcomes. The concentration is higher in raisins because drying removes ~80% of the water, concentrating the acid by the same factor that it concentrates calories: 4.29 times.
The treatment timeline
If your dog eats grapes or raisins, the window for intervention closes fast. Cornell University’s Riney Canine Health Center publishes this timeline:
What happens and when
Case fatality data (Sutton et al. 2009)
The most cited case series on grape and raisin toxicosis in dogs comes from Sutton and colleagues (2009), reviewing 49 cases reported to the Veterinary Poisons Information Service (VPIS):
| Metric | Value | Source |
|---|---|---|
| Total cases reviewed | 49 | Sutton et al. 2009, VPIS |
| Cases from raisins/sultanas | 36 (73.5%) | Sutton et al. 2009 |
| Cases from grapes | 13 (26.5%) | Sutton et al. 2009 |
| Fatal outcomes (total) | 17 (34.7%) | Sutton et al. 2009 |
| Fatal from raisins | 12 of 17 | Sutton et al. 2009 |
| Fatal from grapes | 5 of 17 | Sutton et al. 2009 |
| Fatality rate, raisin cases | 12/36 = 33.3% | Computed from Sutton 2009 |
| Fatality rate, grape cases | 5/13 = 38.5% | Computed from Sutton 2009 |
The fatality rates for grape-only and raisin-only cases are close (38.5% vs 33.3%) — the higher case count from raisins reflects their greater concentration, not a lower lethality per exposure. Both forms are dangerous. The sample size (49 cases) is small, and these figures predate the tartaric acid identification, so they should be read as “documented outcomes in reported cases,” not as population-level statistics.
Why this page does not use the RER / 10% treat ceiling
Every other fruit page on this site builds its answer from the same chain: RER = 70 × kg0.75, then MER, then the 10% treat ceiling, then grams. Grapes break that framework. The 10% rule is about calories — it says treats should not exceed 10% of daily energy needs. Grapes are not a calorie problem; they are a toxicology problem. A single grape (~3.3 g, ~2.3 kcal) is trivially small in calorie terms — it would take 30+ grapes to reach the 10% ceiling for a 30 lb dog — but that same grape may contain enough tartaric acid to trigger kidney failure in a sensitive individual.
So the RER chain is shown here only to make the contrast explicit: the calorie framework says “you could feed dozens,” while the toxicology data says “dozens can kill.” The two frameworks disagree because they answer different questions. For grapes, the toxicology answer wins.
RER = 70 × 13.610.75 = 496 kcal
MER (neutered adult) = 496 × 1.4–1.6 = 694–794 kcal/day
10% treat ceiling = 69–79 kcal
Grapes at 69 kcal/100 g → ceiling = 101–115 g = 31–35 grapes
But the APCC lower toxic threshold is 136 g = ~41 grapes.
The calorie ceiling and the toxic threshold are close enough that a dog could eat its entire daily treat budget in grapes and be at the edge of the documented toxic range. This is why the calorie framework is the wrong tool for grapes.
Raisins are more dangerous than grapes
The drying process concentrates everything except water. The numbers:
| Property | Grapes (fresh) | Raisins (dried) | Factor |
|---|---|---|---|
| Energy (kcal/100 g) | 69 | 296 | 4.29× |
| Water content | 80.54% | 16.57% | −79.4% |
| Toxic threshold (g/kg) | 10–30 | 3 | 3.3–10× |
| Grapes to reach 3 g/kg raisin equivalent | ~12.9 g/kg | 3 g/kg | — |
One tablespoon of raisins (~15 g) for a 30 lb dog is 1.1 g/kg — below the Morrow threshold of 3 g/kg, but above the WebMD conservative line of 0.73 g/kg. Two tablespoons puts a 30 lb dog at 2.2 g/kg, right at the edge. Three tablespoons (3.3 g/kg) exceeds the published kidney failure threshold.
Body weight threshold table
| Dog weight | kg | Grapes at 10 g/kg | Grapes at 30 g/kg | Raisins at 3 g/kg | WebMD line (1/10 lb) |
|---|---|---|---|---|---|
| 5 lb | 2.27 | 23 g / 7 grapes | 68 g / 21 grapes | 7 g / 0.5 tbsp | 1 grape |
| 10 lb | 4.54 | 45 g / 14 grapes | 136 g / 41 grapes | 14 g / 0.9 tbsp | 1 grape |
| 20 lb | 9.07 | 91 g / 28 grapes | 272 g / 82 grapes | 27 g / 1.8 tbsp | 2 grapes |
| 30 lb | 13.61 | 136 g / 41 grapes | 408 g / 124 grapes | 41 g / 2.7 tbsp | 3 grapes |
| 40 lb | 18.14 | 181 g / 55 grapes | 544 g / 165 grapes | 54 g / 3.6 tbsp | 4 grapes |
| 50 lb | 22.68 | 227 g / 69 grapes | 680 g / 206 grapes | 68 g / 4.5 tbsp | 5 grapes |
| 60 lb | 27.22 | 272 g / 82 grapes | 817 g / 248 grapes | 82 g / 5.4 tbsp | 6 grapes |
| 70 lb | 31.75 | 318 g / 96 grapes | 953 g / 289 grapes | 95 g / 6.3 tbsp | 7 grapes |
| 80 lb | 36.29 | 363 g / 110 grapes | 1089 g / 330 grapes | 109 g / 7.3 tbsp | 8 grapes |
| 100 lb | 45.36 | 454 g / 138 grapes | 1361 g / 412 grapes | 136 g / 9.1 tbsp | 10 grapes |
| 120 lb | 54.43 | 544 g / 165 grapes | 1633 g / 495 grapes | 163 g / 10.9 tbsp | 12 grapes |
Grape count uses 3.3 g/grape (USDA Thompson Seedless average). Raisin tablespoons use 15 g/tbsp. These are risk thresholds from published data, not safe feeding amounts. Any ingestion warrants a veterinary call.
Related foods and cross-references
- Raisins — dried grapes, 4.29× more concentrated. The same toxicity applies at a lower gram threshold.
- Sultanas and currants — also dried grapes (Vitis vinifera), same toxic principle.
- Zante currants — often confused with true currants (Ribes spp.); Zante currants are miniature raisins and are toxic to dogs.
- Grape juice and wine — contain tartaric acid; believed toxic, though less studied than whole fruit.
- Cream of tartar — potassium bitartrate, the salt of tartaric acid; identified as toxic to dogs in the same 2021 research.
- Foods containing raisins — mince pies, hot cross buns, Christmas cake, trail mix, oatmeal raisin cookies. These are common sources of accidental ingestion.
- See also: Can Dogs Eat Apples and Can Dogs Eat Blueberries for fruits that are safe for dogs.
FAQ
Can one grape kill a dog?
There is no published “one grape kills” case in the peer-reviewed literature, but one grape (~3.3 g) for a small dog (e.g. 5 lb / 2.27 kg) is 1.45 g/kg — below the APCC threshold of 10 g/kg but above the WebMD conservative line. The unpredictability of individual sensitivity means a single grape cannot be ruled out as harmless. The safe answer is: call your vet if your dog eats any amount.
How many grapes are toxic to a dog?
The APCC documented harm at 10–30 g of grapes per kg of body weight. For a 30 lb dog that is 136–408 g, or about 41–124 grapes. However, some dogs develop kidney failure below this range — the dose-response is unpredictable. The Morrow 2005 threshold for raisins (3 g/kg) is much lower because raisins are 4.29× more concentrated.
Are raisins more dangerous than grapes?
Yes. Raisins are dried grapes — the drying process removes ~80% of the water, concentrating tartaric acid by roughly the same factor (4.29×). The published toxic threshold for raisins (3 g/kg) is 3.3–10 times lower than for fresh grapes (10–30 g/kg). In the Sutton 2009 case series, 73.5% of reported cases involved raisins.
What should I do if my dog ate a grape?
Call your veterinarian or a pet poison hotline immediately — do not wait for symptoms. The ASPCA Animal Poison Control Center is 1-888-426-4435 (consultation fee applies). The Pet Poison Helpline is 1-855-764-7661. Early treatment (within 2–6 hours) may involve inducing vomiting; after that, IV fluids and kidney monitoring for 48+ hours are standard. Blood tests may be normal in the first few hours, so repeat testing over 2–3 days is often recommended.
Why are grapes toxic to dogs but not humans?
The 2021 research identified tartaric acid as the likely culprit. Dogs appear to metabolize tartaric acid differently than humans do — the specific mechanism is still under study. Tartaric acid is present in grapes at 0.35%–1.1% (up to 2%), and also in tamarinds and cream of tartar. Humans have consumed tartaric acid safely for centuries (it is used in baking and winemaking), but dogs develop acute kidney injury from doses that are harmless to us.
Can dogs eat grape leaves or grape jelly?
Grape leaves contain tartaric acid and are not recommended for dogs. Grape jelly and grape jam are also considered unsafe because they contain grape-derived compounds. This page does not cover these products in detail — they are different concentrations and different questions. The safest policy is to keep all grape products away from dogs.
Sources
- Grape and raisin toxic dose thresholds (10–30 g/kg) — ASPCA Animal Poison Control Center (APCC), as cited in veterinary toxicology literature.
- Raisin kidney failure threshold (3 g/kg) — Morrow et al. 2005, cited in Veterinary Poisons Information Service case reviews.
- Case fatality data (49 cases, 17 fatal) — Sutton et al. 2009, Veterinary Poisons Information Service (VPIS).
- Tartaric acid identification (0.35%–1.1%) — Gray et al. 2023, Clinician’s Brief; connection to cream of tartar and tamarinds.
- Treatment timeline (6–24 h onset, 1–3 day progression, 12 h vomit visibility) — Cornell University Riney Canine Health Center.
- Grape nutrient data (69 kcal/100 g, water 80.54%) — USDA FoodData Central, SR Legacy, fdcId 174683.
- Raisin nutrient data (296 kcal/100 g, water 16.57%) — USDA FoodData Central, SR Legacy, fdcId 168166.
- Grape weight (~3.3 g per Thompson Seedless grape) — USDA FoodData Central household weight data.
- RER formula: 70 × kg0.75 — National Research Council, Nutrient Requirements of Dogs and Cats (2006).
- WebMD conservative risk line (1 grape per 10 lb) — WebMD Pets, “Why Dogs Can’t Eat Grapes.”