Basic technique, Ramblings
comments 5

Onion Size, or How Big is a Large Onion?

Onions, lined up by size from small to large

What Size is my Onion

I don’t sweat onion size. Most of my recipes are flexible; if I call for a large onion and you use a medium onion, you’ll be fine. In other words, size doesn’t matter.

Except when it does.

I’m working on my vegetable broth recipe, and I want to get the right ratio of onion, celery, and carrot to water. (3:2 water to vegetables, and 3:2:1 onion to carrot to celery.) To do that right, I need to do it by weight; to give you instructions, I need to know what “2 large onions, chopped” actually means. Testing time! I went to the store, bought a range of onions, and got out my kitchen scale. Here’s what I found.

How much does a Small onion weigh?

5 ounces or less, averaging 4 ounces

How much does a Medium onion weigh?

5 to 8 ounces, averaging about 6 ounces

How much does a Large onion weigh?

8 to 12 ounces, averaging about 10 ounces

How much does an Extra-Large onion weigh?

12 ounces and up, averaging 16 ounces

 Onion Sizes (By Weight) 
Onion Average Weight Sports Ball
Size Weight Range Comparison
Small 4oz / 115g 5 oz or less Racquetball
Medium 6oz / 170g 5 to 8 oz Baseball
Large 10 oz / 285g 8 to 12 oz Softball
Extra-Large 16oz / 454g 12oz or more Shot Put

Most of the onions at the store are large to extra-large onions (in the onion bin) or medium (in a three-pound mesh bag.) I buy large onions – I want to pick good-looking ones from the bin. (That’s why most of my recipes call for large onions.)

What do the Feds have to say?

The USDA has a different grading standard, based on size instead of weight:

 Onion Sizes (By Diameter, USDA Size Classifications) 
Size Designation (in inches)
Small 1 to 2.25
Repacker 1.75 to 3
Medium 2 to 3.25
Large 3 and up
Colossal 3.75 and up

United States Standards for Grades of Onions (Other Than Bermuda- Granex-Grano and Creole Type) []

And, there you have it. (“It” being one large onion, minced.)

What do you think?

Questions? Other ideas? Leave them in the comments section below.

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Thai Curry Paste – Weight vs Volume

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Filed under: Basic technique, Ramblings


Hi! I’m Mike Vrobel. I’m a dad and an enthusiastic home cook; an indie cookbook author and food blogger with a day job, a patient spouse, and three kids who would rather have hamburgers for dinner.


  1. Razzy 7 says

    In recipes it would be helpful to know how many cups or partial cups of onion a recipe calls for and what size or perhaps diameter onion will yield that amount.

    Sometimes it matters little, but sometimes it can make a difference – for example in the veggie broth recipe Mike is working on. While the quantity of ingredients often technically may not matter, to get a similar tasting broth to whatever Mike comes up with the quantity will matter.

  2. Thanks for posting this. It’s something I’ve wondered about for a long time!


  3. Chris L says

    Thanks Mike! I love this kind of info. However, is there any way you can add an addendum on how those sizes translate into “cups, diced” per onion? There are a LOT of frustrating recipes out there that call for “cups” of vegetables, especially when it comes to onions, celery, and carrots. Nobody buys vegetables like that so it drives me crazy when the ingredients are listed out that way.

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