[WheelsAtLarge]

The real answer, a little more than the people around you. Here's a simple example, the upper middle class in Manhattan will need enough to keep their lifestyle plus however much more so they are not at the bottom of the social class. Let's guess $350,000 a year. Now go to Nigeria where the per capita GNP is $1,200 a year and you give a person $5000 a year then that person would jump up with joy.

There's not one number. The number is relative to where you live.

Here's a quote I like:

"When a man sits with a pretty girl for an hour, it seems like a minute. But let him sit on a hot stove for a minute — and it's longer than any hour. That's relativity." A. Einstein

It doesn't fit 100% but you get the idea.