Dogs & cats · Free tool

Onion & garlic toxicity calculator

Onion, garlic, leeks, and chives (the Allium family) damage a pet's red blood cells and cause anemia. Garlic is several times more potent than onion, and cooking or drying — like onion or garlic powder — concentrates the toxin rather than removing it. Cats are more sensitive than dogs, and because the damage builds over days, signs are often delayed. This estimate is tuned toward the more-sensitive cat; enter what your pet ate, and when in doubt, call your vet or a pet poison line.

The reference food. Around 5 g/kg can harm a cat; dogs are affected at higher amounts.

Estimate for triage only, based on Allium toxicity thresholds from the Merck Veterinary Manual and ASPCA Animal Poison Control. Thresholds are set to the more-sensitive cat, and toxicity also depends on the individual pet and repeated exposure — so a low estimate never means "safe." When in doubt, call.

Sources: Merck Veterinary Manual — Allium species (Onions, Garlic) Toxicosis in Animals; ASPCA Animal Poison Control — People Foods to Avoid Feeding Your Pets

How much onion or garlic is too much?

Each cell is roughly the amount at which this tool starts telling you to call — 1 g/kg of onion-equivalent. Below a number here still isn't “safe”: it is the point at which concern begins, not the point at which harm does.

Amount of onion or garlic, by pet weight and type, at which this calculator's first warning band begins
WeightRaw onionCooked onionRaw garlicGarlic powderOnion powder
5 lb2 grams1 gram0 grams0 grams0 grams
10 lb4 grams3 grams0 grams0 grams0 grams
20 lb9 grams6 grams1 gram0 grams1 gram
40 lb18 grams12 grams3 grams1 gram2 grams
70 lb31 grams21 grams6 grams2 grams3 grams

Rounded from the same thresholds the calculator above uses. Individual sensitivity, other ingredients, and your pet's health all move the real number — which is why every band here still ends in “call.”

Common questions

How much onion or garlic is toxic to dogs and cats?

Red-blood-cell damage is expected at around 5 grams of onion per kilogram of body weight in a cat, and dogs are affected at higher amounts — but sensitivity varies and the effect builds with repeated exposure, so this calculator starts flagging concern from about 1 g/kg. Garlic is roughly five times stronger than onion, and powders are far more concentrated still, so even small amounts of garlic powder in seasoning or a small piece of garlic bread can matter for a cat or small dog.

Is garlic worse than onion for pets?

Yes — gram for gram, garlic is about five times more potent than onion, and dehydrated garlic or onion powder is more concentrated again. That's why a pinch of garlic powder in a recipe can be more of a concern than a similar weight of raw onion.

What are the signs of onion or garlic poisoning?

The hallmark is anemia from damaged red blood cells: tiredness, weakness, pale or yellowish gums, faster breathing, and reddish-brown urine. Vomiting or diarrhea can come first. The catch is timing — signs often don't appear for several days after eating, so a normal-looking pet today doesn't rule it out.

My pet ate a small amount of garlic — will they be okay?

Often a tiny, one-time taste causes no visible problem, but because cats and small dogs are sensitive and the effect is cumulative, it's worth noting the amount and your pet's weight and calling your vet or a pet poison line to check. Avoid giving any garlic or onion — including garlic supplements marketed for pets — without veterinary advice.

Read nextSymptoms, timeline, and what the vet will doThe full guide to onion or garlic — what to watch for and how long it takes to show.

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These tools estimate risk — they don't replace your veterinarian and can't examine your pet. For anything worrying, or when in doubt, get a free triage assessment or call your vet.