Convert Onion from Whole Onions to Ounces

Onion converter

Use the tool below to convert onion from Whole Onions to Ounces.

Onion size swings from a 70 g small to a 150 g large, more than double. Setting the size below means “1 cup chopped” comes out right whether your onions are small or jumbo.

How many ounces is one medium onion?

One medium onion is about 3.88 ounces. A small onion is about 2.47 ounces and a large one about 5.29 ounces, so set the size selector to match what you have. Use the converter above for any amount, or the chart below for the most common quantities.

Out of onion? See onion substitutes →

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 our Garlic converter.

Enter an amount, pick your units, and set the size for counting whole onions.

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Onion sizeSize applies to whole onions (small / medium / large).

Result

3.88 oz

Common Onion conversions

Quick reference for onion at medium size. Switch the size in the converter above for small or large.

onions	Ounces
1 onion	3.88 oz
2 onions	7.76 oz
3 onions	11.64 oz
4 onions	15.52 oz
5 onions	19.4 oz
6 onions	23.28 oz

Onion conversion chart

The chart below shows how whole onions (medium size) convert to cups, grams and ounces.

onions	oz	cups	cups (US)	g	lb
1 onion	3.88 oz	0.66 cups	0.69 cups (US)	110 g	0.24 lb
2 onions	7.76 oz	1.32 cups	1.38 cups (US)	220 g	0.49 lb
3 onions	11.64 oz	1.98 cups	2.06 cups (US)	330 g	0.73 lb
4 onions	15.52 oz	2.63 cups	2.75 cups (US)	440 g	0.97 lb
5 onions	19.4 oz	3.29 cups	3.44 cups (US)	550 g	1.21 lb

Onion varieties and best uses

The conversions above are the same whatever variety you use; the difference is what each is good for. Here is how the common onion varieties compare.

Variety	Best for
Yellow / brown	All-purpose cooking, soups, caramelising: balanced and sweetens when cooked.
Red	Raw in salads and pickling: mild, colourful; also good roasted.
White	Mexican dishes and salsa: sharp and clean raw.
Sweet (Vidalia / Walla Walla)	Onion rings and raw slices: low pungency, high sugar.
Shallot	Dressings and pan sauces: delicate, subtle flavour.

Which should I pick?

For everyday cooking, soups, and caramelising, a yellow / brown onion is the default, with the most balanced flavour. For raw use in salads, salsa, or pickling, a red or sweet (Vidalia / Walla Walla) onion is milder. White onions suit Mexican dishes; shallots are the delicate choice for dressings and pan sauces.

Frequently Asked Questions

How many ounces is one medium onion?: One medium onion is about 3.88 ounces, a small one about 2.47 ounces and a large one about 5.29 ounces. Onions vary in size, which is the main reason a recipe that counts onions can still vary in weight. Set the size selector to match what you have, then read the exact figure for any count above. Open the onion converter
Which onion variety should I use?: For everyday cooking, soups, and caramelising, a yellow / brown onion is the default, with the most balanced flavour. For raw use in salads, salsa, or pickling, a red or sweet (Vidalia / Walla Walla) onion is milder. White onions suit Mexican dishes; shallots are the delicate choice for dressings and pan sauces.

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