The short answer: an onion typically weighs about 100 to 200 grams (3.5 to 7 ounces), feeling heavy because its layers are packed with water.
Onion weight by type
Onions range from small shallots to large Spanish onions. The weights below cover common cooking onions.
| Type (example) | Typical weight |
|---|---|
| Small onion | about 70-110 g (2.5-4 oz) |
| Medium onion | about 110-170 g (4-6 oz) |
| Large onion | about 200-300 g (7-11 oz) |
| Shallot | about 20-50 g (0.7-1.8 oz) |
What affects onion weight
- Size. A large onion can weigh three times a small one.
- Variety. Spanish, yellow, red, and shallots differ in typical size.
- Water content. Onions are packed with water and feel dense.
- Skin. The papery skin adds only a little weight that is removed.
- Freshness. Onions dry out slowly in storage and lose some weight.
How onion weight compares
A medium onion weighs about the same as a medium apple, while a large one is closer to a full can of soup.
Frequently asked questions
How much does an average onion weigh?
A medium onion weighs about 110 to 170 grams. Large onions can reach 300 grams.
How much does a large onion weigh?
A large onion usually weighs about 200 to 300 grams.
How many onions are in a kilogram?
About five to eight medium onions make up a kilogram.
