Can onions fit a keto diet?

Fits only in a measured amount

Yes, but only in a measured amount: raw onions can fit a keto diet.

The 1 cup measure weighs 160 g and contains 10.8 g calculated net carbs, alongside 6.8 g calculated net carbs per 100 g. The documented composition basis is 30 g Onions, white, raw; 60 g Onions, yellow, raw; and 10 g Onions, red, raw, with red onions and onions, NFS listed as source attributes.

Check another amount

Values update from the same USDA record. They do not estimate a personal carb target or ketosis response.

Amount in grams

Listed source portion: 1 cup (160 g).

Calculated net carbs

10.8 g

Total carbohydrate

13.5 g

Dietary fiber

2.7 g

Editorial illustration of Onions, raw.

Nutrition facts for Onions, raw

Source-portion carb band: Higher net carbs per listed portion. The category is based only on calculated net carbs for the listed portion: 5 g or less, more than 5 g to 10 g, or more than 10 g. Your total intake, preparation, and clinical context can change how a food fits your own plan.

Nutrient	Per listed portion: 1 cup (160 g)	Per 100 g
Energy	61 kcal	38 kcal
Protein	1.4 g	0.9 g
Total fat	0.1 g	0.1 g
Saturated fat	0.1 g	0 g
Total carbohydrate	13.5 g	8.5 g
Dietary fiber	2.7 g	1.7 g
Calculated net carbs	10.8 g	6.8 g
Total sugars	9.3 g	5.8 g
Sodium	1.6 mg	1 mg
Potassium	273.6 mg	171 mg

The table keeps the USDA basis separate from the selected portion.

1. Food formOnions, raw
2. USDA per-100 g basis6.8 g calculated net carbs
3. Selected source portion10.8 g calculated net carbs
4. Calculation boundaryPortion value is calculated from the cited 100 g record and portion weight

Explore this food category

Compare this form and portion with other records in keto vegetables. The category hub explains why forms, preparation, and portions should not be treated as interchangeable.

For meal-level context, use the keto food list.

How the calculation works

Calculated net carbs = total carbohydrate − dietary fiber. For this USDA record, that is 8.5 g − 1.7 g = 6.8 g per 100 g. Net carbs is a planning convention used on this site; it is not a separate USDA nutrient field or a regulatory nutrition-label value. This calculation does not automatically subtract sugar alcohols.

For the underlying approach and its limitations, see how net carbs are explained and the net-carb calculator.

Food record and source

• USDA food description: Onions, raw
• FoodData Central ID: FDC ID 2709795
• Dataset: Survey (FNDDS) FNDDS 2021-2023 (2024-10-31)
• Record publication date: 10/31/2024
• Selected portion: 1 cup (160 g)

The nutrition values are reported by the USDA per 100 g. The per-portion column above is calculated from that value and the USDA portion weight; no household measure was invented for this page.

1. USDA FoodData Central, Survey (FNDDS) FNDDS 2021-2023 (2024-10-31), FDC ID 2709795. https://fdc.nal.usda.gov/food-search/?query=2709795, https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_survey_food_json_2024-10-31.zip

Compare related foods

• Onions, cooked, no added fat — Compare another form of onions.
• Beets, raw — Compare another food in the vegetables whole food group.
• Carrots, raw — Compare another food in the vegetables whole food group.

Browse all Food Database entries or start with the keto food list for practical meal-planning context.

Frequently Asked Questions

Can onions fit a keto diet?

Raw onions can fit a keto diet only in a measured amount, with 1 cup (160 g) containing 10.8 g calculated net carbs.

How many net carbs are in Onions, raw?

The listed 1 cup (160 g) has 10.8 g calculated net carbs. Per 100 g, the record has 6.8 g calculated net carbs.

How are net carbs calculated for Onions, raw?

247-Keto calculates net carbs as total carbohydrate minus dietary fiber, capped at zero. For this record, that is 8.5 g total carbohydrate minus 1.7 g fiber per 100 g. Sugar alcohols are not subtracted by this calculation.

Where do these Onions, raw nutrition facts come from?

The values come from USDA FoodData Central's Survey (FNDDS) FNDDS 2021-2023 (2024-10-31) release, FDC ID 2709795. The page preserves the listed food description and portion weight so the comparison is traceable.

Article history

1. September 11, 2026Updated after final factual and editorial review
2. August 24, 2026First published