How many calories in
white onion?
White Onion is 40 calories per 100g — very low for vegetables. Low-cal enough to fill out plates without much trade-off.
Common serving sizes.
Calories scale with portion. Here's how a typical white onion serving translates in your tracker:
What 40 calories means.
Very low calorie — at 40 kcal per 100g, white onion adds volume to a meal without meaningfully denting a calorie deficit.
White Onion vs. similar foods.
How white onion stacks up on calories and protein against foods people commonly compare it to:
Skip the lookup. Snap the plate.
Point your iPhone camera at white onion and Spotwell's AI estimates the portion and macros in a few seconds. Check it, adjust anything that looks off, and log it.
Download on theApp StoreQuick answers.
How many calories in white onion?
White Onion has approximately 40 calories per 100g. A typical serving — 3 oz (85g) — comes in at 34 calories.
How much protein is in white onion?
1.1g of protein per 100g. That puts white onion at roughly 2.8g of protein per 100 calories — a useful lens when comparing to other vegetables sources.
How do I log white onion accurately?
The simplest method: weigh it on a kitchen scale, then enter grams in your tracker. With Spotwell, you can skip the scale — point the camera at the plate and the AI estimates the portion in a few seconds. Adjust the value if it looks off.
Is white onion good for weight loss?
It depends on your overall calorie target. White Onion is naturally low-calorie at 40 kcal per 100g, so it's easy to fit into a deficit.