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If anything is certain about credit scores it’s that they change. How much they change can depend heavily on your decisions, and if you want to save money, there are steps you can take to attain and maintain a high credit score.

How you manage your debt determines whether you have great credit, bad credit or something in between, and the difference can cost you hundreds of thousands of dollars in your lifetime.

Consider this example: A 37-year-old woman living in California who has fair credit would spend about $87,000 more in interest over her lifetime than if she had good credit, and $130,000 more than if she had excellent credit. The savings from having good credit alone could cover the cost of four years at a public university in California, so when it comes to lifetime savings, your credit score is a huge deal.

That example comes from’s lifetime cost of debt calculator. You can plug in your own information to figure out how much your credit score is costing you, but here’s how it works:

We chose a woman living in California to illustrate the cost of credit, because women have a longer life expectancy than men, and California is the most populated state in the country. The median age of the American population is 37.2 years, according to the 2010 census.

This 37-year-old California woman has the average California mortgage ($747,332), takes out an average auto loan every seven years ($18,000) and is paying down an average amount of credit card debt ($5,700 with a $170 monthly payment). On the VantageScore 3.0 scale, she has fair credit, between a 620 and 679 score.

With fair credit, she’ll pay $639,240 in interest during her lifetime. By changing only the credit score in this equation — an upgrade to good credit, or a score between 680 and 739 — cuts that figure to $552,179. If she had excellent credit (740 to 850), her lifetime cost of debt would be $508,592.

By always making loan and credit card payments on time, keeping her revolving debt levels low, applying for new credit infrequently and avoiding negative information on her credit reports, like collection accounts, the 37-year-old California woman could improve her credit and save money over time. Almost everyone has room for improvement in his or her credit scores (and who doesn’t like to save money?). You can see what areas of your credit profile need work by getting a free credit report summary on, which includes two free credit scores every month as well.

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