Onions come in various sizes, with diameters ranging from a minimum of 10 millimeters to over 70 millimeters.
Specific size categories are often used in trade, with terms like "large" (64 mm+), "medium" (51-64 mm), and "small" (38-51 mm) being common.
Onions are typically globular (round), spherical (perfectly round), or ellipsoidal (slightly elongated).
The most common onion color is yellow, but they can also be white, red, or even purple.
Some countries and organizations have established specific grading and quality standards for onions, which may define aspects like minimum size, allowed defects, and acceptable storage conditions.
