Is a 20-inch chain too short for a man?

No, a 20-inch chain generally isn't too short for a man. In fact, 20 inches is the average length for a men's necklace. At this length, a necklace will usually fall to the collarbone. Men may also wish to wear shorter or longer necklaces, depending on their preferences. Find a wide variety of chain necklaces on 1stDibs.