Red Onions Calories and Nutrition Facts
Red Onions has 44 calories per 100 g, with 0.9 g protein, 9.9 g carbs and 0.1 g fat. Official USDA analytical record: Onions, red, raw (FDC ID: 790577).
One standard serving of red onions (1 Onion, edible (197 g)) contains 87 calories, 1.8g protein, 19.5g total carbs (15.2g net carbs), and 0.2g fat. Per 100 grams, it supplies 44 calories.
Energy density
0.44 kcal/g
very low
Protein / 100 kcal
2 g
satiety per calorie
Net carbs / 100 g
7.7 g
carbs minus fibre
100 kcal portion
227 g
≈ 8 oz
- Sugars
- 11.4g
- Fibre
- 4.3g
- Saturated fat
- 0g
- Sodium
- 2mg
Red Onions Portion & Serving Size Comparison
Compare calories, carbs, net carbs, and macros across common household measurements.
| Portion Size | Weight | Calories | Total Carbs | Net Carbs | Protein | Fat |
|---|---|---|---|---|---|---|
| 100 g | 100 g | 44 kcal | 9.9 g | 7.7 g | 0.9 g | 0.1 g |
| 1 Onion, edible (197 g) | 197 g | 87 kcal | 19.5 g | 15.2 g | 1.8 g | 0.2 g |
Onions, red, raw nutrition facts
The table below shows the complete nutritional profile for onions, red, raw per 100 g (the laboratory analytical standard) and per 1 Onion, edible (197 g), alongside the share of the FDA Daily Value each nutrient covers. Most of its calories come from carbohydrate, and it is relatively low in calories.
| Nutrient | Per 100 g | Per 1 Onion, edible (197 g) | % DV* |
|---|---|---|---|
| Calories | 44 kcal | 87 kcal | — |
| Protein | 0.9 g | 1.8 g | 2% |
| Carbohydrate | 9.9 g | 19.5 g | 4% |
| Fat | 0.1 g | 0.2 g | 0% |
| Sugars | 5.8 g | 11.4 g | — |
| Fibre | 2.2 g | 4.3 g | 8% |
| Saturated fat | 0 g | 0 g | 0% |
| Sodium | 1 mg | 2 mg | 0% |
*Percent Daily Value per 100 g, against the FDA reference intakes for adults and children 4+ years (50 g protein, 275 g carbohydrate, 28 g fibre, 78 g fat, 20 g saturated fat, 2300 mg sodium). Total sugars has no Daily Value — the 50 g reference applies to added sugars only, and USDA reports total sugars here.
Red Onions calories by weight: ounces, pounds and grams
USDA publishes this food per 100 g, so here is the same profile converted to the weights a kitchen scale and a US recipe actually use. At 0.44 kcal per gram (very low energy density), you can eat a large volume of this for very few calories, which makes it useful for filling out a meal in a deficit.
| Amount | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| 1 oz (28 g) | 12 kcal | 0.3 g | 2.8 g | 0 g |
| 100 g (3.5 oz) | 44 kcal | 0.9 g | 9.9 g | 0.1 g |
| 4 oz (113 g) | 50 kcal | 1 g | 11.2 g | 0.1 g |
| 8 oz / ½ lb (227 g) | 100 kcal | 2 g | 22.5 g | 0.2 g |
| 1 lb (454 g) | 200 kcal | 4.1 g | 44.9 g | 0.5 g |
Data sourced from USDA FoodData Central Foundation Foods dataset (public domain, CC0). Laboratory food profile and analytical measurements verified under USDA FDC ID 790577.
View raw USDA laboratory entry →How red onions compares to other vegetables
Against the 80 vegetables in this database, red onions ranks 60th lowest in calories and 58th highest in protein. The category averages 50 kcal per 100 g, so this one is 12% below it. The lightest option in the category is pickles, cucumber, dill or kosher dill at 12 kcal per 100 g, and the protein leader is flour, potato at 8.1 g per 100 g.
| Vegetables (by calories) | Calories | Protein | kcal/g |
|---|---|---|---|
| 🍄 Mushroom, enoki | 44 kcal | 2.4 g | 0.44 |
| 🍄 Mushrooms, shiitake | 44 kcal | 2.4 g | 0.44 |
| 🧅 Onions, red, raw (this page) | 44 kcal | 0.9 g | 0.44 |
| 🍽️ Beets, raw | 45 kcal | 1.7 g | 0.45 |
| 🍄 Mushroom, king oyster | 46 kcal | 2.4 g | 0.46 |
Portion planning with red onions
- 100 calories comes to about 227 g (8 oz).
- Fibre density is 5 g per 100 calories, covering 8% of the daily fibre target per 100 g.
- Macro split by calories: 90% carbs, 8% protein, 2% fat.
Nutrient screening detail
The badges near the top of this page come from screening the per-100 g values against the FDA nutrient-content thresholds in 21 CFR 101.54–101.62. The regulations define those claims per reference serving rather than per 100 g, so treat these as a like-for-like comparison between foods, not as a statement about a product label:
- Low fat — 0.1 g per 100 g (≤ 3 g)
- Low saturated fat — 0 g per 100 g (≤ 1 g)
- Sodium free — 1 mg per 100 g (< 5 mg)
Track red onions for free
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Red Onions FAQ & Nutrition Questions
How many calories and carbs are in 1 Onion, edible (197 g) of red onions?
One serving of 1 Onion, edible (197 g) provides 87 calories, 19.5 g total carbs (15.2 g net carbs), 1.8 g protein, and 0.2 g fat.
How many calories are in 100 g of red onions?
Red Onions contains 44 calories per 100 g, with 0.9 g protein, 9.9 g carbohydrate, and 0.1 g fat. Use the interactive calculator above to scale to any custom amount.
What is the USDA FoodData Central (FDC) ID for red onions?
The official USDA FoodData Central ID for "Onions, red, raw" is FDC ID: 790577. You can view the verified laboratory analytical record on the USDA FoodData Central Database.
What is the macronutrient breakdown of red onions?
By calories, red onions is approximately 90% carbohydrates, 8% protein, and 2% fat.
How many calories are in an ounce of red onions?
One ounce (28 g) of red onions has 12 calories, with 0.3 g protein, 2.8 g carbs and 0 g fat. Four ounces (113 g) comes to 50 calories, and a full pound (454 g) to 200 calories.
How much red onions is 100 calories?
About 227 g of red onions supplies 100 calories, because it carries 0.44 kcal per gram (very low energy density). You can eat a large volume of this for very few calories, which makes it useful for filling out a meal in a deficit.
How many net carbs are in red onions?
Per 100 g, red onions has 7.7 g net carbs — 9.9 g total carbohydrate minus 2.2 g fibre.
Is red onions high or low in calories for a vegetable?
Red Onions sits 12% below the vegetables average of 50 kcal per 100 g, ranking 60th lowest of 80 in this category.
Is this nutrition data free to use?
Yes. The data is sourced directly from USDA FoodData Central (CC0 public domain). Viewing and scaling portions here is 100% free with no sign-up — and you can log this food free in our online food diary.