Child support cost?

Can you ladies please tell me an appropriate/expected child support amount for one child (3 month old). Rather than going to court, I just wanted to come up with an agreement with him for how much to give me every month. Is this based on multiple factors (how much he makes, etc), or is there a range that is typical that most people get per month? If you don’t mind sharing how much you get or a range that would be helpful to me. Thanks!