You build it by putting money away for it. If you use a savings account for it, you just aggressively put money into it until it meets your requirement.

How much depends on a variety of factors, but it is best to get at least $1000, and then work up to 3 months expenses, and then see what you need from there. Obviously, the larger the emergency fund, the more one is prepared, but sometimes, one can analyze the risk and make a decision that it only realistically needs to cover a few months at most.

It doesn't make sense for it to cover more than a year for most people.

My advice is:

• Build up a small emergency fund, say, $1000.
• Then contribute a little to it while aggressively paying down the credit cards.
• Resolve to avoid credit card debt and build up your emergency fund.