Convert Onion from Whole Onions to Cups (chopped)
Convert whole onions to cups below. One medium onion is about 0.66 cups, and 2 onions make roughly 1.32 cups.
How many cups is an onion?
One medium onion gives about 0.66 cups of onion when chopped, so 2 onions come to roughly 1.32 cups. A small onion is about 0.42 cups and a large one about 0.9 cups, so set the size selector to match what you have.
Related Onion Ingredients
Already chopping? The chopped onion converter moves straight between cups, grams, and spoons of prepped onion. See our Chopped Onion converter.
Need a milder, more delicate allium? Shallots (20–60 g) suit dressings and pan sauces. See our Shallot converter.
Spring onions (10–25 g) are tender and herbaceous, great raw or as a garnish. See our Spring Onion converter.
Mincing garlic for the same dish? Garlic cloves (2–7 g) bring pungent bite where onion brings sweet body. See what one medium clove is in cups.
Want a crisp, peppery bite? Radishes (8–25 g) are sharp and crunchy, good raw in slaws or quick pickles. See our Radish converter.
Out of onion? See onion substitutes →
Onion converter tool
Enter an amount, pick your units, and set the size for counting whole onions.
Result
0.66 cupsOnion Calculators & Kitchen Tools
Working with onion? These tools handle the jobs a converter cannot.
- Oven to Air Fryer Converter Match the temperature and time when you swap the oven for an air fryer, fan oven, or slow cooker.
- Recipe Scaler Scale any recipe up or down and keep every ingredient in ratio.
Common Onion conversions
Quick reference for onion at medium size. Switch the size in the converter above for small or large.
| onions | Cups (chopped) |
|---|---|
| 1 onion | 0.66 cups |
| 2 onions | 1.32 cups |
| 3 onions | 1.98 cups |
| 4 onions | 2.63 cups |
| 5 onions | 3.29 cups |
| 6 onions | 3.95 cups |
Frequently Asked Questions
- How many cups is one medium onion?
- One medium onion (about 110 g) gives roughly 0.66 cups of chopped flesh. A small one (around 70 g) yields about 0.42 cups and a large one (around 150 g) about 0.9 cups, so set the size selector to match the onions you actually have before you trust the figure. Open onion converter
- How many cups is 2 onions?
- 2 onions are about 1.32 cups. The ratio is fixed, so one medium onion is 0.66 cups and the figure scales in a straight line as you multiply or divide. Scaling a recipe up or down keeps the same proportion, so work from whichever amount your recipe lists. Use the converter above for any other quantity of onion.
- How many cups is 3 onions?
- 3 onions are about 1.98 cups. The ratio is fixed, so one medium onion is 0.66 cups and the figure scales in a straight line as you multiply or divide. Scaling a recipe up or down keeps the same proportion, so work from whichever amount your recipe lists. Use the converter above for any other quantity of onion.
- What is the difference between a metric and US cup?
- A metric cup holds 250 ml while a US cup holds 240 ml, so a US cup is 4% smaller. For chopped onion that gap is small but real, and it adds up across several cups. The guide linked below explains when the difference matters and how to switch between the two so a recipe lands right whichever cup you own. metric v US cup