How Many Calories are in a Yellow Onion: Yellow Onion Calories & Nutrition Guide

Why You Should Know About Yellow Onion Calories

Yellow onions are one of those kitchen staples we often take for granted. They show up in soups, stews, stir-fries, salads, and pretty much any savory dish you can think of. If you're keeping an eye on calories, you've probably asked yourself: how many calories are in a yellow onion? This guide breaks it all down — the numbers, the nutrients, and why this humble vegetable deserves a spot in your diet.

Yellow Onion Nutrition Facts

Here's what you get from a standard serving of raw yellow onion. We're using a medium-sized onion (about 5.3 ounces or 150 grams) and a 3.5-ounce (100-gram) portion for comparison.

Note: DV = Daily Value based on a 2,000-calorie diet.

Health Benefits of Yellow Onions

Yellow onions aren't just low in calories. They pack some real nutritional punch.

• Rich in Vitamin C: One medium onion gives you about 12% of your daily vitamin C needs. That helps with immune function and keeping your skin healthy.
• Antioxidants galore: They're loaded with quercetin, a flavonoid that may help fight inflammation and support heart health.
• Fiber for digestion: With nearly 3 grams of fiber per onion, they help keep things moving and help you feel full.
• Heart-friendly: Naturally low in sodium and virtually fat-free, yellow onions are a smart pick for heart health.
• Prebiotics: The inulin and fructooligosaccharides in onions feed the good bacteria in your gut.

How to Cook With Yellow Onions

Yellow onions are a go-to in American kitchens because their flavor balances out nicely when cooked.

• Sautéing: Start soups, stews, or sauces by cooking diced onion in a little oil until translucent.
• Roasting: Cut into wedges, toss with olive oil and herbs, and roast at 400°F until caramelized and tender.
• Raw in salads: Thin slices add crunch and a mild bite to salads, tacos, and sandwiches.
• Grilling: Brush thick slices with oil and grill for a smoky, sweet side dish.
• Caramelizing: Cook sliced onions low and slow to bring out their natural sugars. Perfect for French onion soup or pizza.

Storing Yellow Onions

Proper storage keeps your onions fresh for weeks.

• Whole, uncut: Keep them in a cool, dry, well-ventilated spot away from light. A pantry works great. Don't store them near potatoes — those release moisture and speed up spoilage.
• Cut onions: Wrap tightly in plastic wrap or put them in an airtight container. Refrigerate and use within 3–5 days.
• Shelf life: Whole yellow onions can last 1–2 months if stored properly. Check regularly for soft spots or mold.
• Freezing: Dice or slice onions, freeze them on a baking sheet, then transfer to a freezer bag. They'll keep for 3–6 months and don't need thawing before cooking.

Frequently Asked Questions

How many calories are in a yellow onion?

A medium yellow onion (about 150g) has around 60 calories. Per 100 grams, it's about 40 calories.

Are yellow onions healthier than red or white onions?

All onion types are nutritious. Yellow ones have slightly more quercetin and a balanced flavor, making them versatile for cooking. Red onions are often eaten raw and have different antioxidants.

Can I eat yellow onions on a low-carb diet?

In moderation, yes. A medium onion has about 14g of carbs and 2.6g of fiber. On a strict keto diet, you'll want to watch your portion size, but many low-carb plans include small amounts of onion.

How do I stop crying when cutting onions?

Chill the onion in the fridge for 30 minutes before cutting. Use a sharp knife to minimize cell damage. Cutting under running water or wearing goggles can also help.

Do cooked onions lose nutrients?

Some vitamin C is lost with heat, but fiber and quercetin stay stable. Cooking can even make some antioxidants easier to absorb.

How many calories are in a cup of chopped yellow onion?

One cup of chopped raw yellow onion (about 160g) has roughly 64 calories.

Are caramelized onions still low in calories?

The onions themselves stay low-calorie, but caramelizing requires oil, which adds calories. Use minimal oil to keep it light.

Can dogs eat yellow onions?

No. Onions are toxic to dogs and cats. They contain compounds that can damage red blood cells. Keep all onion products away from pets.

Where This Data Comes From

Nutrition values in this guide are from the USDA FoodData Central database, specifically for raw yellow onions. Values can vary slightly based on size, growing conditions, and preparation. Always check labels on packaged or processed onion products.