According to the research I made, here are the list of how to tell if a guy has a small package:

• He Is Overly Concerned With His Appearance – He was often examining his flawlessness in the mirror. This is a red flag!
• Wears gray sweatpants a lot – If a guy wears them frequently, it’s possible that it’s the only way his stuff will appear huge. And he’s well aware of the situation.
• The Way The Guy Sits – If he constantly sits with his legs apart, it’s possible he’s attempting to avoid squeezing his big companion. When the legs are crossed, tiny stuff might find a place. Certainly not a big one.
• The larger the nose, the larger the package – The size of the nose, or its length, has been utilized as a predictor of men’s stuff size until recently.
• Shoe Size As An Indicator – There’s a theory that there’s a correlation between a man’s shoe size and his stuff. Small foot = small package.
• Guys who are skinny vs. guys who are overweight – Slim males are considered to have a better package because they have fewer muscles, allowing for more flesh between their legs.
• He’s Repeating That Size Doesn’t Matter – He will not remark the size of the package if he is satisfied with his bundle. Why would he do such a thing? He knows what he has and doesn’t need to persuade anyone.
• Size Of The Hands And Fingers – According to some experts, a man with a longer ring finger than his index finger is more likely to have a large package.

I just summarized the points on the article I saw, click here to know more details,