We've all been lured in by the siren call of better rates, special perks and rewards, or lower fees so that most Americans carry between five and 10 credit cards. The problem is not so much that new credit card offers are so attractive but rather that we do not stop to evaluate which cards we no longer need after opening a new account.

Carrying too many credit cards can wreak havoc with your credit score -- especially if you use too much of your available credit. Of course that leads to an important question -- how many credit cards should you have? Most experts say there really isn't a magic number. It is really more about proportion. Each person, household, or business, should evaluate spending and payment habits. It is important to note that once you start holding a number of credit accounts then your credit report will be impacted simply because you are now at greater risk of racking up debt that you can't handle.

Of course, it does depend somewhat on the type of card and the amount of credit involved. Store credit cards are notorious for impacting your credit negatively. In fact some consumer experts report that every time you open a store credit card, 20 points are taken off your credit score.

So how do you judge whether or not you have too many credit cards? The average person carries 11 "credit accounts" of varying types. Typically, seven are different types of credit cards and four are installment loans for cars, furniture, student loans or mortgages. Most people do not need seven credit cards. Usually two or three is more than sufficient.

Perhaps one will be a store credit card for a merchant that you shop frequently and that will make you eligible for savings and bonuses and another will be one of the major credit cards such as Visa, MasterCard, American Express or Discover that is accepted anywhere.

If you cannot maintain a low or zero balance on your credit cards then you have too many. Most people do need a credit card for emergencies so holding a low interest card can be a help with your personal finances but holding a number of cards that regularly add interest and other fees to your monthly budget is no bargain.

An important rule of thumb to remember is to keep your debt ratio under 50%. If your credit card has a $5,000 limit, don't carry a balance of more than $2,500. Creditors don't like to see a card almost maxed out because it makes you look like a risk who has trouble paying off debt.

The best way to protect your credit is to keep only a reasonable number of credit cards. A reasonable number is determined by your ability to maintain a low balance and make your payments on time. Ideally you should use less than 30% of your credit limit on each card. However, use caution when trimming down the number of credit cards. Some debt advisers warn that closing too many cards at once can cause your debt-to-credit ratio to fall.

For example, if you have $20,000 of potential credit and a $5,000 balance, you are using 25% of your potential. If you shut down a card with a $5,000 balance you will still have $5,000 of debt and only $15,000 of potential, upping your ratio to 33%. It is better to close excess accounts over several months (as you also pay down your balances). Also, don't close all your oldest accounts if you find abetter card. A long, successful credit history will do much to improve your credit rating so maintaining some older accounts until your more recent accounts age is a good idea.

If used appropriately, credit cards are a safe way to buy goods because they offer protection against fraud that checks and cash can't guarantee, especially when it comes to return policies or fraudulent purchases. However it is up to the account holder to use that credit cautiously. Maintaining fewer accounts means less chance of late fees and increased rates. Having more credit and more credit cards does not necessarily make a good rating. The key factors are job stability, paying as agreed and paying on time. Keeping up with payments on a few cards will build a better credit rating than opening numerous credit-card accounts.

There is no right number of credit cards for everyone. It depends on how much you spend and how much you can pay off. The key idea is to maintain a sense of proportion.