system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how is a serving size determined?

For example, how does the Hershey company know that a package of King size Reese cups is a serving? How does Pringles know that 1 oz of cheddar cheese Pringles is a serving? What is a serving based off of?
gpt
It's all made up. 

At least in the US, there's no standard. All they're required to do is show the amount of servings in the product and what each serving represents. i.e. the company arbitrarily decides how many grams/ounces/any random measurement equals 1 serving.