How Many Calories Are In Yellow Onion? | Kitchen Facts

Calories In Yellow Onion: Portion Guide

Yellow onion calories are easy to ballpark once you know the weight. Raw onions average about 40 kcal per 100 g, so the math stays simple across servings. A medium onion at home lands near 110 g (about 44 kcal), while a packed cup of chopped onion is closer to 160 g (about 64 kcal). You can confirm those figures through MyFoodData and the USDA SNAP-Ed onion page, which uses the same federal datasets.

Raw Yellow Onion Calories By Common Serving

Serving	Approx. Weight	Calories
Per 100 g	100 g	~40 kcal
1 cup chopped	160 g	~64 kcal
1 medium onion	~110 g	~44 kcal
1 small onion	~70 g	~28 kcal
1 large onion	~150 g	~60 kcal

How Much Does An Onion Weigh?

Stores sell a mix of sizes. In a loose bin, many onions are large; bagged onions skew medium. Recipe writers often assume a medium onion around 110–150 g. If you need accuracy for tracking, weigh a quarter or half, then scale up. That trick speeds up prep, keeps your numbers tidy, and avoids overthinking it.

What Changes The Calories? Raw Vs Cooked

Heat by itself doesn’t add energy. Water drives off and weight falls, so calories per gram change a bit. The big swing comes from fat. A tablespoon of oil can double the energy in a pan of onions. When you want low energy per bite, stick to dry-heat without oil or simmer onions in stock.

Boiled Or Steamed

Boiled, drained onions come in at about 92 kcal per cup cooked (roughly 210 g). That’s still modest and works well in soups and purées where you’re not adding fat to the pot. Numbers come from the same dataset used by MyFoodData for cooked onions.

Sautéed And Caramelized

Cooked yellow onions sautéed in oil can reach ~123 kcal per 100 g, because the onions absorb fat while the water cooks off. That’s delicious, just account for the oil in the pan and any butter you finish with.

Yellow Onion Calories By Method

Method & Portion	Calories	Notes
Raw, 100 g	~40 kcal	Base reference
Raw, 1 cup chopped (160 g)	~64 kcal	Recipe standard
Boiled, 1 cup cooked (~210 g)	~92 kcal	No added fat
Sautéed, 100 g (with oil)	~123 kcal	Oil absorbed

Macro And Micro Profile Of Yellow Onions

Carbs, Fiber, And Natural Sugar

Onions are mostly water with a small carb load. In 100 g raw, you’ll see roughly 9–10 g carbs with 1–2 g fiber and about 4–5 g natural sugars. That’s why the taste shifts sweet as they brown. The carbohydrate profile in federal data aligns with that 40 kcal baseline per 100 g.

Protein And Fat

Protein and fat are both low. Expect about a gram of protein and a tenth of a gram of fat per 100 g raw. Even when you boil onions, those numbers barely change. When you pan-cook, it’s the added oil that moves the needle, not the onion itself.

Vitamins And Minerals

Raw yellow onions provide small amounts of vitamin C and B6, plus potassium, with trace amounts of others. You won’t use onions as your sole source for these, but they support variety in a meal pattern built around vegetables. The current guidance encourages mixing vegetable types across the week; that includes “other vegetables” like onions along with dark-green, red-orange, legumes, and starchy picks in a balanced plate pattern as outlined in the Dietary Guidelines.

Portion Math You Can Trust

Fast Conversions For Recipes

Need the energy for half an onion? Halve the number for your size class. Quartering a large onion for fajitas? Divide the total by four. Working from cups? A level cup of finely chopped yellow onion is a tidy ~160 g. That makes a quick mental shortcut: cup × 0.64 = kcal for raw chopped onion.

When You’re Tracking Oil

Two teaspoons of oil add roughly 80 kcal. A slick in a nonstick pan is often less than a teaspoon. Measure once, look at the sheen, and you’ll know how much your pan really needs. If a recipe lists “2 tbsp oil,” consider starting with half and adding only if the onions look dry.

Practical Ways To Use Yellow Onions With Goals

For Lower-Calorie Cooking

• Build flavor with time, not fat. Sweat onions in a covered pan with a splash of water or stock until translucent, then finish uncovered to drive off moisture.
• Roast thick wedges on a rack. You get browning with minimal oil if you keep space between pieces.
• Pickle thin slices. A quick brine adds pop for tacos or grain bowls with minimal energy.

For Muscle-Friendly Meals

• Pair sautéed onions with lean protein. Think chicken breast, turkey mince, or tofu.
• Add beans. Red or black beans bring fiber and extra protein to a skillet with onions and peppers.
• Toss into egg scrambles. A half cup of sautéed onion spreads sweet depth through a whole pan.

Common Questions, Straight Answers

Is A Yellow Onion Low Calorie?

Yes. At ~40 kcal per 100 g, yellow onions fit easily into energy-aware cooking. Even a full cup chopped is ~64 kcal, which is friendly for soups, stews, and sautés that rely on vegetables for bulk and flavor.

Raw Vs Cooked: Which Is “Better”?

They both have a place. Raw keeps the count lowest and adds crunch. Boiled or steamed stays light and brings sweetness. Pan-cooking with oil gives richer flavor, and you decide how much oil to add based on your target for the meal.

Do Different Onion Types Change The Number?

Yes, a bit. Sweet onions can skew slightly lower per 100 g raw but still live in the same ballpark. The approach doesn’t change: weigh or use cup measures, apply the 40 kcal per 100 g baseline, then factor in any cooking fat.

Reliable Sources Behind These Numbers

The calorie counts above come from federal nutrition datasets and tools that draw from them. For raw onions and standard kitchen measures, see MyFoodData. For a simple “1 medium onion” reference with calories and grams, check the USDA SNAP-Ed onion page. If your plate pattern follows national guidance, the vegetable subgroup mix recommended in recent Dietary Guidelines will fit onions right in.