It really depends on what type of Card you have. Here is a list of ways that you might find on your card to get your balance.
1. Any ATM machine * might have to pay a fee
2. 1-800 number on the back of card * probably a fee
3. Some cards show balance on receipt after you purchase something.
4. The Internet webpage of your card holder. * Usually Free.
Again it depends on what card you have.