Onion Nutrition Facts, Calories by Size, Slice and Cup

USDA's "Onions, raw" record covers mature dry bulb onions, and this page uses it for the everyday types. Green onions (scallions) are harvested young, with their leaves, and have their own USDA data.

• Yellow onions: the all-purpose cooking onion and most of the US crop; they turn sweet and brown when cooked slowly.
• White onions: sharper and crisper, common in Mexican cooking and raw toppings.
• Red onions: mild enough to eat raw in salads, sandwiches and pickles; the color comes from pigments in the outer layers.
• Sweet onions: lower in pungency rather than much higher in sugar, so they taste milder raw.

Cooking an onion does not add calories by itself, but it removes water. Sauteed onions shrink, and caramelized onions can cook down to a small fraction of their raw weight, so a spoonful of caramelized onion holds the calories and sugar of a much larger amount of raw onion, plus any butter or oil used. USDA keeps separate records for boiled and sauteed onions. Cutting an onion releases a sulfur gas that irritates the eyes; chilling the onion first and using a sharp knife reduces it.

• French onion soup. Slowly caramelized onions in beef broth, topped with bread and melted cheese. Butter · White Bread
• Onion rings. Thick onion slices battered or breaded and fried, so most of their calories come from the coating and oil. All-Purpose Flour · Egg
• Pico de gallo and salsa. Raw chopped onion with tomato, chili and lime. Tomato · Avocado
• Soffritto and mirepoix. Onion cooked with carrot and celery as the base of soups, stews and sauces. Carrot · Olive Oil · Butter
• Pickled red onions. Thin slices quick-pickled in vinegar, salt and a little sugar. Table Salt · Sugar

Keep whole dry onions in a cool, dry, dark place with air around them, such as a mesh bag or basket, and away from potatoes, which give off moisture that makes onions sprout and spoil sooner. Sweet onions have more water and keep for less time, so refrigerating them, wrapped individually, helps. Cut onions go in a sealed container in the refrigerator.

Weigh onions peeled and trimmed, in the raw state, and enter them in the label generator with the rest of the recipe. Any cooking loss belongs to the whole batch: weigh the finished soup, jam or sauce and divide it into servings, which the recipe nutrition calculator does for you. For fried onions or onion rings, include the batter and the oil absorbed. Check the reference amount for your product type in the RACC lookup.