Free dog calculator
Dog Grape & Raisin Toxicity Calculator
This dog grape toxicity calculator counts the grapes, raisins or currants your dog ate against the risk line in the Merck Veterinary Manual: more than one per 10 pounds of body weight. Below that line isn’t safe either, and the result tells you why.
- Risk line from the Merck Veterinary Manual
- Shows the math behind every number
- Free, no sign-up or email
This is an estimate built from published veterinary figures, not a diagnosis. Grapes and raisins have no amount known to be safe, so call your vet or ASPCA Animal Poison Control at (888) 426-4435 (a consultation fee may apply) whatever the number says.
How the grape calculator works
Merck names tartaric acid as one proposed toxic principle in grapes, raisins and tamarinds. Dogs clear organic acids poorly, so it can build up in the kidney tubules. In general, Merck says more than one grape or raisin per 4.5 kg (10 pounds) of body weight may contain enough tartaric acid to pose a risk to the kidneys.
The calculator divides your dog’s weight by 4.5 kg to get that line, then compares the number eaten. Merck counts a grape and a raisin the same way, one fruit each, and puts Zante currants in the same Vitis family.
The risk line by weight
| Dog’s weight | Merck’s line (grapes or raisins) |
|---|---|
| 5 lb (2.3 kg) | 0.5 |
| 8 lb (3.6 kg) | 0.8 |
| 11 lb (5.0 kg) | 1.1 |
| 16 lb (7.3 kg) | 1.6 |
| 25 lb (11.3 kg) | 2.5 |
| 32 lb (14.5 kg) | 3.2 |
| 50 lb (22.7 kg) | 5.0 |
An 11 lb miniature dachshund crosses the line at two grapes. Since the tartaric acid in each fruit varies, Merck describes the effects as variable, and that’s why a count under the line is still a reason to call.
How many raisins are in a box?
Counting raisins after the fact is hard, so here’s what common amounts hold, from USDA FoodData Central’s household measures. The last column is the heaviest dog for which that amount is still over Merck’s line of one per 10 pounds.
| Amount | About how many | Over the line for any dog under |
|---|---|---|
| 1 mini box of raisins (0.5 oz, 14 g) | 30 | 296 lb |
| 1 snack box of raisins (1.5 oz, 43 g) | 91 | 910 lb |
| 1 oz of raisins | 60 | 600 lb |
| 1 cup of raisins, not packed (145 g) | 307 | 3,069 lb |
| 10 grapes (49 g) | 10 | 100 lb |
| 1 cup of grapes (151 g) | 31 | 308 lb |
A single half-ounce mini box, the lunchbox size, is over the line for any dog under about 300 pounds. In practice, that means every dog. Grapes add up just as fast for a dachshund: two grapes already put an 11 lb miniature over the line.
Foods that hide raisins
Many raisin scares don’t start with a box of raisins. They start with something that has raisins in it. When a vet posted a holiday warning about raisins on r/DogAdvice, the most upvoted reply pointed out that A.1. steak sauce contains raisins. We checked the label: A.1. Original lists raisin paste, and it also lists dried garlic and dried onion, so it counts against the onion calculator too.
Steak sauce
A.1. Original lists raisin paste, dried garlic and dried onion. The label doesn’t say how much, so there’s no count to enter. Call with the bottle.
Baked goods
Oatmeal raisin cookies, cinnamon raisin bread, hot cross buns, fruitcake and mince pies, whose filling is mostly dried fruit.
Cereal and snacks
Raisin bran, granola, trail mix and yogurt-covered raisins. Chocolate-covered raisins count twice: here and in the chocolate calculator.
Counting what’s gone
Estimate how many raisins were in the part that’s missing and enter that count above. If you can’t, call with the package.
What happens after a dog eats grapes
- Most affected dogs start vomiting or have diarrhea, according to Merck.
- Kidney failure with little or no urine can develop. Merck says most dogs that reach no urine output die or are euthanized.
- For a large amount, or diarrhea within 12 hours, Merck recommends at least 48 hours of IV fluids.
Grape and raisin questions
My dog ate one grape. Is that okay?
For a dog over 10 pounds, one grape sits at or under Merck’s line, but it isn’t a guaranteed safe amount. Call your vet or the poison line, and watch for vomiting over the next 6 to 12 hours. Our guide to grapes and raisins covers the rest.
Are raisins worse than grapes?
Merck’s risk line counts them the same, one grape or one raisin per 10 pounds. Raisins are smaller and often eaten by the handful, so the count climbs faster.
What about tamarind or cream of tartar?
Merck groups tamarinds with grapes and raisins, and cites a report of kidney injury in dogs after eating cream of tartar and tamarinds. The calculator can count tamarind pieces, but there’s no per-piece line, so call either way.
Sources
- Merck Veterinary Manual, Grape, Raisin, and Tamarind Toxicosis in Dogs: tartaric acid, the per-4.5 kg risk line, timing and treatment (read October 2026).
- USDA FoodData Central, SR Legacy records 168165 (raisins, seedless) and 174683 (grapes, raw): counts per ounce, box and cup.
- A.1. Original Steak Sauce ingredient list, as published on US grocery retailer product pages (read October 2026).
- ASPCA Animal Poison Control Center: phone line and fee note (read October 2026).