That depends on how big a bunch you buy, and how small or large you chop the onions.
0.1872 cups of chopped onions.
Four chopped green onions will give you around 1/2 cup, although it would greatly depend on the thickness and length of the green onions. And by "green onions", we will assume you are referring to the long, thin onions, also referred to as scallions or spring onions.
The web references vary and show medium onions as 3/4 to 1 cup chopped and large onions as 1 to 1.5 cups chopped.
If chopped that is about 6 cups.
A medium onion normally yields about one cup of chopped onions. A small onion normally yields about one half cup of chopped onions.
Onions vary greatly in size, but most large onions yield about 1 to 1 1/2 cups.
you can get almost one cup of green peppers from a medium chopped green pepper.
1 medium onion is 1/2 cup chopped, do the math.
If chopped, about 1 cup.