[veyron]

What is your burn rate? Take the average of the expenses over the last year. That will dictate how long you can continue without having to worry about outside income.

Now, I assume you have the idea already, so do you expect to turn profitable (or large enough to raise angel/vc money) by the time youve burned through the savings?

Do you have kids? If so, you need to worry much more about the buffer

But even if all of that is squared away, natural instincts will tell you its a bad idea. Especially if you have been in the working world for a long time. This is natural, and expected, that you would be nervous about making the jump. That being said, there are many people (do a search) that have done the same thing on weaker bases.