Extra Money?

In "The Singer Solution To World Poverty," Singer says that anyone with a surplus of money should donate to charity and help save lives rather than spending it on unnecessary things like going out out to dinner, or buying a new TV. I agree that people with enough extra money should give to people who need it more than them. However, the question is how much money should you choose to donate? I guess it depends on your personal idea of comfortable living. I don't think that living with just the bare minimum to survive is something most people want to do. That being said, everyone has a different idea of what the bare minimum is. It is impossible to reach a standard baseline for charity, but if everyone donated the extra money they had, no matter what your idea of 'extra money' is, then the world definitely would be better off.