How many calories and carbohydrates are in the various types of onion and what is the the water content?

An average onion has 35 calories, 3 grams of carbohydrate, and is 92% water.

An average red onion has 49 calories, 2.3 grams of carbohydrate, and is 90% water.

A spring onion (scallion) has 23 calories, 2 grams of carbohydrate, and is 88% water.