Dog Onion Toxicity Calculator: How much onion is deadly for my dog?

dog with onions

How much onion is toxic to dogs ?

Ingesting onions in quantities as small as 0.5% of a dog's overall body weight can be potentially fatal. This means a 20 pound dog only needs to eat 1.6 ounces of onions to be in serious trouble.

To put this in perspective, here is a list of common dishes and the amount of onion they contain.

  • Spaghetti Sauce - Approximately 2 oz of onions per cup

  • Vegetable Soup - Around 1.5 oz of onions per serving

  • Beef Stew - Roughly 2.5 oz of onions per serving

  • Onion Dip - About 3 oz of onions per half-cup

  • Meatloaf - Approximately 1 oz of onions per slice

  • Curry Dish - Around 2 oz of onions per serving

  • Onion Rings - Roughly 1 oz of onions per 3 rings

  • Fried Rice - About 1 oz of onions per cup

  • Salad with Onions - Approximately 0.5 oz of onions per serving

  • Grilled Onion Burger - Roughly 2 oz of onions per burger

To figure out if your dog has ingested a toxic amount of onion, use my free calculator below. Simply enter your dog's weight and the approximate amount of onion they consumed.


The calculator above is a great tool to use to determine if your dog may have ingested a toxic amount of raw onions. But, what about other foods containing onions; can dogs have onion rings, for example?

Can dogs eat onion rings?

No, your dog should not eat onion rings. Even if the onion is covered in thick batter it still may contain enough N-propyl disulfide to harm your dog.

Now, can one onion ring kill a dog? Probably not, but that answer largely depends on the size of the onion and the size of your dog. In most cases, a single onion ring probably won't harm your dog much.

Will a small amount of onion hurt my dog?

As long as the amount of onion ingested does not equal to or exceed 0.5% of your dog's total body weight, it should not hurt your dog. However, you should always monitor your dog's behavior for any changes after they consume onion.

What are the symptoms of onion poisoning in dogs?

Below are common symptoms associated with onion poisoning in dogs.

  • Lethargy or weakness

  • Reduced appetite or anorexia

  • Pale or bluish gums

  • Increased heart rate

  • Panting or difficulty breathing

  • Reddish or darkened urine

  • Vomiting or diarrhea

  • Abdominal pain or discomfort

  • Disorientation or incoordination

  • Excessive drooling

What to do if dog ate small piece of onion

If your dog at a small piece of onion, follow these steps.

  • Don't panic: This won't help your dog.

  • Call your local vet for a consultation

  • Remove any remaining onions from your dog's reach to prevent further ingestion

  • Observe your dog closely for any symptoms of onion poisoning

  • Be ready to provide your vet with information, such as how much onion your dog ate and when

  • Follow your vet's advice, which may include inducing vomiting or bringing your dog in for treatment

  • Keep a watchful eye on your dog over the next few days for any delayed symptoms

  • Consider implementing safety measures to prevent similar incidents in the future, like securing food items out of your dog's reach

How to prevent dogs from eating onion

Try keeping your onions and onion products like onion powder away from the area your dog eats. Also, if you have young children, store your onion laced products on a high counter or in a cabinet.

Kids love to share food with their dogs and may accidentally poison them as a result.

If you want to keep your dog safe and find out more about toxic foods and substances for your dogs, bookmark my other calculators: Dog Chocolate Toxicity Calculator, Dog Grape Toxicity Calculator, and Dog Xylitol Toxicity Calculator. For context, Xylitol is a potentially fatal substance for dogs that's found in a ridiculous amount of foods we eat everyday!

Matt Irving is the CEO of Super Easy Tech, LLC.
Matt is the founder of Make It Super Easy and creator of Super Easy CRM. He is a beast of a software engineer, blogger, and gamer. Feel free to connect on any of the platforms listed below.

Posted by: Matt Irving on 12/04/2023