Sizes, grades and packs
Onion sizes and grades: jumbo, colossal, medium and US No. 1
Onion size is set by diameter: medium runs about 2 to 3.25 inches, jumbo is 3 inches and up, colossal 3.75 and up, super colossal 4.5 and up. Grade is a separate quality standard, and US No. 1 is the workhorse grade covering mature, firm, well-shaped onions free of the serious defects, so the same field can price several ways once you split it by size and grade.
Updated Jul 10, 2026
Cite
Onion size and onion grade are two different things, and a shipping-point price depends on both. Size is diameter. Grade is quality. The same field, packed into different sizes and grades, prices several different ways, which is why a report line always names both.
Size is diameter
The trade sorts onions by bulb diameter, and the standard classes run like this. Medium is roughly 2 to 3.25 inches. Jumbo, the common large size, is about 3 inches and up. Colossal is 3.75 inches and up. Super colossal is 4.5 inches and up. There are smaller classes below medium, boilers and creamers, for specialty packs. Size is purely about diameter, not quality: a jumbo and a medium can be identical onions grown in the same row, just sorted by how big they came out. Buyers care because different buyers want different sizes.
Who buys which size
Size maps to the customer. Foodservice leans on jumbos and bigger, because a kitchen slicing onions all day wants fewer larger bulbs and less peeling per pound. Retail bags skew toward medium, the size that looks right in a shopper's hand and fills a 2 or 3-lb bag cleanly. The colossal and super colossal end serves specialty demand like blooming-onion cuts. Because the same crop feeds all of them, one field can be sorted into several sizes and each one finds its own price. That is the same-field-several-prices reality on every size-split report.
Grade is quality
Grade is a separate standard, set by USDA, describing condition rather than size. US No. 1 is the grade that covers the bulk of fresh-market onions. In plain terms it means onions that are mature, fairly firm and fairly well shaped, with similar varietal characteristics, and free from decay and free from damage by the serious defects: sprouting, seedstems, splits, sunscald, sunburn, doubles, bottlenecks and the rest. It is not a perfection standard, it is a sound-commercial-onion standard. Reports also carry ungraded lots, marked N/A, where no grade was stated. US No. 1 is the benchmark most quotes reference.
See it split out
The 50-lb sack table above is one pack held constant so the other variables show. Every FOB quote on this site names its size and its grade, because both move the number. Hold the pack and the variety steady, change the size from medium to jumbo to colossal, and the price steps with it. That is not the market being noisy. It is the same onion sorted into what different buyers want, priced accordingly.
Know Your Onions reports sizes and grades as USDA publishes them, straight off the shipping-point line.
Now look at the live data
Common questions
How big is a jumbo onion?
A jumbo onion is about 3 inches in diameter and up. It is the common large size for foodservice. Colossal starts around 3.75 inches and super colossal around 4.5 inches.
What size is a medium onion?
A medium onion runs roughly 2 to 3.25 inches in diameter, the size most common in consumer retail bags. It sits below jumbo on the size scale.
What does US No. 1 mean for onions?
US No. 1 is USDA's workhorse grade for fresh-market onions: mature, fairly firm and fairly well shaped, free from decay and free from damage by defects like sprouting, seedstems, splits and sunscald. It describes quality, not size.
Is onion size the same as grade?
No. Size is diameter, like medium or jumbo. Grade is a quality standard, like US No. 1. A report line names both because each one affects the price separately.