How do I convert cups to US cups for any recipe?

Switching between metric cups and US cups is a fixed volume ratio that applies to any ingredient, since one US cup is 240 ml and one metric cup is 250 ml. The volume converter at the link below covers cups, US cups, millilitres, tablespoons and teaspoons in both directions.

What is the difference between a metric cup and a 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.

Convert Onion from Cups (chopped) to US cups (chopped)

Onion converter

Use the tool below to convert onion from Cups (chopped) to US cups (chopped).

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 US cups is 1 cup of onion?

One cup of onion is 1.04 US cups. A US cup holds 240 ml and a metric cup 250 ml, so the gap is small and fixed for any ingredient. Use the converter above for any amount, or the volume converter linked below for millilitres, tablespoons and more.

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.

No measuring cups? The tool below gets you close, and a measuring cup set keeps every batch the same.

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

Convert from

Convert to

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

Result

1.04 cups (US)

Common Onion conversions

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

Cups (chopped)	US cups (chopped)
0.25 cups	0.26 cups (US)
0.5 cups	0.52 cups (US)
0.75 cups	0.78 cups (US)
1 cup	1.04 cups (US)
1.5 cups	1.57 cups (US)
2 cups	2.09 cups (US)
3 cups	3.13 cups (US)

Onion conversion chart

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

cups	cups (US)	onions	g	oz	lb
0.25 cups	0.26 cups (US)	0.38 onions	41.75 g	1.47 oz	0.09 lb
0.5 cups	0.52 cups (US)	0.76 onions	83.5 g	2.95 oz	0.18 lb
1 cup	1.04 cups (US)	1.52 onions	167 g	5.89 oz	0.37 lb
1.5 cups	1.57 cups (US)	2.28 onions	250.5 g	8.84 oz	0.55 lb
2 cups	2.09 cups (US)	3.04 onions	334 g	11.78 oz	0.74 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 US cups is 1 cup of onion?: One cup of onion is 1.04 US cups, and two cups are 2.09 US cups. A US cup holds 240 ml against a metric cup's 250 ml, so the gap is small and the same for any ingredient. Use the converter above for any cup amount of onion. Open the onion converter
How do I convert cups to US cups for any recipe?: Switching between metric cups and US cups is a fixed volume ratio that applies to any ingredient, since one US cup is 240 ml and one metric cup is 250 ml. The volume converter at the link below covers cups, US cups, millilitres, tablespoons and teaspoons in both directions. Cups to US cups converter
What is the difference between a metric cup and a 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
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.

Other produce

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